Homogeneous Catalysis NIOK

1

Homogeneous CatalysisHomogeneous CatalysisNIOK

SchuitSchuit Institute of Catalysis Institute of Catalysis

D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK Intro_01

SchiermonnikoogSchiermonnikoogNovember 30 November 30 –– December 4, 2009December 4, 2009

Homogeneous CatalysisHomogeneous CatalysisOverviewOverview•• IntroductionIntroduction

History, general principles & aspectsHistory, general principles & aspects•• OrganometallicsOrganometallics

•• Elementary Reaction StepsElementary Reaction Steps

•• Homogeneous Homogeneous Catalytic ProcessesCatalytic ProcessesHydrogenationHydrogenationHydroformylationHydroformylationCarbonylation of Methanol (Carbonylation of Methanol (Monsanto acetic acid & Monsanto acetic acid & acetic anhydride process)acetic anhydride process)

•• ConceptsConcepts


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK

HydrocyanationHydrocyanationWackerWacker--Hoechst OxidationHoechst OxidationOligomerizationOligomerizationMetathesisMetathesisPolymerizationPolymerization

2

CatalysisCatalysis•• ““A catalyst accelerates a chemical reaction without A catalyst accelerates a chemical reaction without

appearing in any of the products. An equilibrium is appearing in any of the products. An equilibrium is equilibrated faster, but the position of the equilibrium will equilibrated faster, but the position of the equilibrium will not be changed”not be changed”

•• Catalysis is of major socioCatalysis is of major socio--economic importance to our society. In economic importance to our society. In order to solve the future problems connected with limited order to solve the future problems connected with limited resources and energy, as well as environmental protection, there is resources and energy, as well as environmental protection, there is no way without efficient catalysis.no way without efficient catalysis.

not be changed”not be changed”


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK Catalysis_01

no way without efficient catalysis.no way without efficient catalysis.

•• Catalysis is a highly interdisciplinary discipline, bringing together Catalysis is a highly interdisciplinary discipline, bringing together top of the art fields of science and technology.top of the art fields of science and technology.

ΔG

Rate Acceleration by CatalysisRate Acceleration by Catalysis

AB

A+B

AB

A+B

ΔGcatΔGG



catalyseduncatalysed

reaction coordinate

Hessen/Elsevier

3

Selectivity by CatalysisSelectivity by Catalysis

Reactions: DC A + B

ΔGdΔGc ~~ΔGc,cat ΔGd,cat>

dc



A+BC DDC A+B

catalyzednoncatalyzedHessen/Elsevier

A Catalytic CycleA Catalytic Cycle

S CatAB

S

A

S

B Cat A Cat A

S S



BHessen/Elsevier

4

Free Energy Profile of a Catalytic CycleFree Energy Profile of a Catalytic Cycle

ΔG1 in the scheme

A+B ΔG3

ΔG2ΔG1 >> ΔG2 ΔG3,

first step israte determining

ΔGo



AB

Hessen/Elsevier

The Catalytic CycleThe Catalytic Cycle

s bstrates bstratecatalystcatalyst--substratesubstrate

complexcomplex tt

transition statetransition stateactive catalystactive catalystcatalyst precursorcatalyst precursor

substratesubstrate complexcomplex reagentreagent



catalystcatalyst--productproductcomplexcomplexproductproduct

Asymm-sw11

5

CatalysisCatalysis



Substrates can be converted into high value Substrates can be converted into high value products by very small amounts of a catalystproducts by very small amounts of a catalyst

Asymm-sw9

Types of CatalysisTypes of Catalysis

Biocatalysis(enzymes)

HomogeneousCatalysis

HeterogeneousCatalysis

PPd

PhPh

PtPt

Pt

SiO2



P OPh Ph

PtPt

Pt

2

Hessen/Elsevier

6

Types of Catalysis: CharacteristicsTypes of Catalysis: Characteristics

Biocatalysis(enzymes)

HomogeneousCatalysis

HeterogeneousCatalysis

Complex bio-molecules / organisms

Geneticmodification

Well-definedmolecular species

Easy to study andto modify

Active species onsolid support

Difficult to study andto modify specifically



Fermentation-likeprocesses (but rangeof conditions expanding)

Difficult to handlein processes(e.g. cat-productseparation)

Convenient inmost processes

Hessen/Elsevier

Catalysts for Homogeneous CatalysisCatalysts for Homogeneous Catalysis

- Lewis Acids and Bases- Electrons- Bronsted Acids and Bases

- Main group metal compounds

- coordination/activation of substrate

(Organometallic) Transition-metal catalystsare able to combine several functions, e.g.:

- Transition metal compounds Main group metal compounds



- spatial restriction of the reaction environment- facilitating reaction steps using metal orbitals- redox processes- bringing reagents together in the coordination sphere

Hessen/Elsevier

7

Catalysis With BrCatalysis With Brøønsted Acids & Basesnsted Acids & Basesan Examplean Example

HH

Methanolysis of propene oxide

O OMe

OHOMe

OH

HO

H

MeOH

H -H



OH

OMeMeOH MeObase O

OMeMeOH

O

Hessen/Elsevier

Catalytic Cycle and Elementary StepsCatalytic Cycle and Elementary Steps

- LLn-1M

HH

YY 18 16 18 16

oxidative additionoxidative addition

++ HHYY

Ln-2MHH

YY

RHH

-- LLMMLLnn MMLLnn--11

dissociationdissociation

ν = 18, 16ν = 18, 16 ν = 16, 14ν = 16, 14

ν = 18, 16ν = 18, 16

ν = 16, 14ν = 16, 14


associationassociationν = 18, 16ν = 18, 16reductive eliminationreductive elimination



+ L RLn-2M

YY

HH

RYY

HH

ν = 16, 14ν = 16, 14

insertioninsertionassociationassociation

ν = 18, 16ν = 18, 16

Catgen_sw1

8

Transition metalTransition metal

Factors Controlling Activity and SelectivityFactors Controlling Activity and Selectivityin a Metal Complexin a Metal Complex

R

•• e--configuration (d0-d10)•• orbital symmetry•• number of coordination sites•• ion or atom radius•• ionic or neutral•• nature of counter ions

LigandsLigands•• donor / acceptor properties•• dissociation constant•• space filling (cone angle)•• chelate effect•• bite angle•• symmetry



ML

L

R

Substrate & SolventSubstrate & Solvent•• in principle like ligands

Catgen_sw2last change: 090909









9

Organometallic CompoundsOrganometallic Compounds

•• Organometallic compounds are compounds that containOrganometallic compounds are compounds that containat least one Mat least one M--C bondC bond

OClCli l li l lNi

C

C CC

OOO

FePt

Cl

Cl

Cltypical examplestypical examples

but notbut notNi

CN

CNNC

NC 2-


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK Organomet_01

•• Of Importance to reactivityOf Importance to reactivitypolarity of the Mpolarity of the M--C bondC bondnumber & nature of the valence orbitals and electronsnumber & nature of the valence orbitals and electrons

Types of MTypes of M--C Bonds in the Periodic TableC Bonds in the Periodic Table



electron deficiency compoundselectron deficiency compoundsionic compoundsionic compoundsdd--metals, Mmetals, M--C C σσ--bonding and bonding and ππ--bondingbonding

covalent Mcovalent M--C C σσ--bonding bonding metalloidsmetalloidsnonnon--metalsmetals

Organomet_02

10

Organometallic CompoundsOrganometallic CompoundsHistoryHistory

Year Organomet. comp. Name Remarks1827 [Pt(C2H4)Cl3]K Zeisse’s salt 1. olefin. comp.1841 [Me2As]2O Bunsen Kakodyl oxide[ 2 ]2 y1850-1900 R2Zn Frankland valence theory1868 [Pt(CO)Cl2]2 Schützenberger 1. carbonyl complex1890 Ni(CO)4 Mond founder of ICI1900-20 RMgX Grignard, Barbier synthetic aplic. of OM

R4Si KippingR2Hg, R3As Schlenk

1909 (Me)3PtI Pope 1. trans. metal alkyl



1919 Cr-arene compounds Heim1920 Et4Pb, R2Te Midgley industrial application1920-50 RNa, RK, RLi Ziegler, Gilman, Wittig basis of org. alkali chem.1928 M(CO)n Hieber systematic investigation1931 H2Fe(CO)4 Hieber

Organometallic CompoundsOrganometallic CompoundsHistoryHistory

Year Organomet. comp. Name Remarks1938 Roelen hydroformylation1951 Ferrocene Pauson, Kealy, Miller organo transition metal chem.95 e oce e auso , ea y, e o ga o t a s t o eta c e .1953 R3Al Ziegler polymerization, renaissance of main

group OM chem.1955 Cr(C6H6)2 Fischer1959 [(C3H5)PdCl]2 Smidt, Hafner allyl complexes

[(C4Me4)NiCl2] Criegee1961 (PPh3)2Ir(CO)Cl Vaska reversible O2 binding1963 Nobel Prize Ziegler, Natta ethene polymerization



1964 (CO)5W=C(OMe)Me Fischer 1. carbene complex1965 (PPh3)3RhCl Wilkinson, Coffey homogeneous hydrogenation catalyst1970 Wilkinson steric blocking of b-elimination1973 Nobel Prize Wilkinson, FischerFrom then explosive development

11

MainMain--Group Organometallic CompoundsGroup Organometallic Compounds•• Electronegativity and ionElectronegativity and ion--charactercharacter

polarization of the metalpolarization of the metal--C bondC bond M — Cδδ++ δδ--

Percentage ion character after PaulingPercentage ion character after Pauling

% ionic = 1 – e1/4(ENA- ENB)2

HF 50 C-Cs 57HCl 20 C-Na 47

compound % ionic C-M bond % ion character


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK main-gr_organo 21

HCl 20 C Na 47HBr 10 C-Li 43HI 5 C-Mg 34

C-Al 22C-Si 12C-As 6

considerably covalent bondingconsiderably covalent bonding

Structure ExamplesStructure ExamplesElectron deficiency compoundsElectron deficiency compounds

tetrameric [MeLi]tetrameric [MeLi]44 and [and [nnBuLi]BuLi]44

Ionic compoundsIonic compoundsPhPh33CC-- NaNa++

Covalent MCovalent M--C C σσ--bonding bonding MeMe44SiSi



MM--C C σσ--bonding and bonding and ππ--bondingbonding

CrC C

COOO

12

Structure ExamplesStructure Examples•• Influence of the metal with the same organic group Influence of the metal with the same organic group RR

Na

1) M = Na, Si, Fe R = C5H5- (Cp-)

ionic-lattice

NaHSi

Si-C σ-bondingR3Si moves around the ring

Fe

Ferrocene, π-complex

2) M = K, MgX, Pd, Ni R = C3H5 (allyl)



K

ionic

MgX (ROR)2

σ-bonding

Pd

Pd-C σ-bond+ π-contribution

Ni

π-allyl complex

Structure ExamplesStructure Examples•• Influence of the organic group Influence of the organic group RR with the same metalwith the same metal

[MeLi]4 tetramer e- deficiency compound

ionic

[Me2Be]x polymer e- deficiency compound

tBu Be monomer linear σ-bonds

Li

BeBeMe

MeBe

Me

Me



Bu2Be monomer, linear σ-bonds

Be

13

•• general: the more polar the bond , the more reactivegeneral: the more polar the bond , the more reactive

•• As a rule of thumb for (As a rule of thumb for (AA) elements) elements

R-Mδ- δ+

periodicperiodic

Reactivity of Organometallic CompoundsReactivity of Organometallic Compounds

periodic periodic tabletable

((AA)) RR--Cs > RCs > R--Rb > RRb > R--K > RK > R--Na > RNa > R--LiLiRR22Ca > RCa > R22Mg > RMg > R22BeBe

((BB)) RR--Cu > RCu > R--Ag > RAg > R--AuAu



RR22Zn > RZn > R22Cd > HgRCd > HgR22

For elements of group (For elements of group (BB) the rule inverts.) the rule inverts.The least reactive compound of (The least reactive compound of (AA) is still) is stillmore reactive than the most reactive of (more reactive than the most reactive of (BB))

RR--Li > RLi > R--CuCu

RR22Be > RBe > R22ZnZn

main-gr_organo 25

Main Group Organometallic CompoundsMain Group Organometallic CompoundsMetal valence orbitals: 1 x s and 3 x pMetal valence orbitals: 1 x s and 3 x p

Octet ruleOctet ruleNoble gas configuration with 8 valence electronsNoble gas configuration with 8 valence electrons

CH3

AlCH3 CH3

CH3

SiCH3CH3

CH3

CH3

As CH3CH3

:



6 v.e. 8 v.e. 8 v.e. includinglone pair

Lewis acid Lewis base

Hessen/Elsevier

14

Transition Metal Organometallic CompoundsTransition Metal Organometallic CompoundsMetal valence orbitals: 5 x d, 1 x s, and 3 x pMetal valence orbitals: 5 x d, 1 x s, and 3 x p

1818--electron ruleelectron ruleNoble gas configuration with 18 valence electronsNoble gas configuration with 18 valence electrons

2 x C5H51 x FeFe

= 2 x 5 = 10 v.e.= 8 v.e.

18 v.e.

1 C H = 5 v e

saturated



ZrCH3 CH3

CH3

1 x C5H5

3 x CH3

1 x Zr

= 5 v.e.

= 3 x 1 = 3 v.e.= 4 v.e.

12 v.e. Lewis acidicHessen/Elsevier

e- available hapticity Ligand Metal-ligand structure1 η1 H M-H1 η1 Cl, Br, I M-X1 η1 OH M-OH1 η1 CN M-C≡N1 η1 CH3, alkyl M-CH3, M-R2 η1 CO PR3 M C≡O M PR

Counting ElectronsCounting Electrons

•• Metal atoms and ligands are Metal atoms and ligands are treated as neutraltreated as neutral

2 η CO, PR3 M-C≡O, M-PR3

2 η1 NH3, H2O M-NH3, M-OH2

2 η1 alkylidene M=CR2

2 η2 alkene M

2 η1 =O, =S M=O, M=S3 η1 NO(linear) M-N≡O

3 η3 C3H5, allyl M

•• Count all valence eCount all valence e-- of the of the mmetal & all etal & all ee-- donated by the donated by the ligandsligands

•• Correct for charges of the Correct for charges of the complexcomplex



3 η1 alkylidyne M≡C-R

4 η4 1,3-diene, C4H6

M

5 η5 cyclopentadienyl,C5H5 M

6 η6 arene, C6H6

M

15

ClMn(CO)5 MnMn 7 e7 e--

ClCl 1 e1 e--

5 CO5 CO 10 e10 e-- =>=> 18 e18 e--

Cp2Fe (ferrocene) FeFe 8 e8 e--

Counting ElectronsCounting ElectronsExamplesClMn(CO)5 MnMn 7 e7 e--

ClCl 1 e1 e--

5 CO5 CO 10 e10 e-- =>=> 18 e18 e--

Cp2Fe (ferrocene) FeFe 8 e8 e--

2 Cp2 Cp 10 e10 e-- =>=> 18 e18 e--

CpRe(CO)3 ReRe 7 e7 e--

3 CO3 CO 6 e6 e--

CpCp 5 e5 e-- =>=> 18 e18 e--

Cr(CO)6 CrCr 6 e6 e--

6 CO6 CO 12 e12 e-- =>=> 18 e18 e--

Fe(CO)5 FeFe 8 e8 e--

2 Cp2 Cp 10 e10 e-- =>=> 18 e18 e--

CpRe(CO)3 ReRe 7 e7 e--

3 CO3 CO 6 e6 e--

CpCp 5 e5 e-- =>=> 18 e18 e--

Cr(CO)6 CrCr 6 e6 e--

6 CO6 CO 12 e12 e-- =>=> 18 e18 e--

Fe(CO)5 FeFe 8 e8 e--



Co2(CO)8 CoCo 9 e9 e--

4 CO4 CO 8 e8 e--

CoCo--CoCo 1 e1 e-- =>=> 18 e18 e--

5 CO5 CO 10 e10 e-- =>=> 18 e18 e--

Ni(CO)4 NiNi 10 e10 e--

4 CO4 CO 8 e8 e-- =>=> 18 e18 e--

Co2(CO)8 CoCo 9 e9 e--

4 CO4 CO 8 e8 e--

CoCo--CoCo 1 e1 e-- =>=> 18 e18 e--

5 CO5 CO 10 e10 e-- =>=> 18 e18 e--

Ni(CO)4 NiNi 10 e10 e--

4 CO4 CO 8 e8 e-- =>=> 18 e18 e--

Organomet_06

Organometallic CompoundsOrganometallic Compounds18 Electron Rule18 Electron Rule

•• The 18The 18--electron rule recognizes the special stability of electron rule recognizes the special stability of ee----

configurations corresponding to the noble gas at the end of the configurations corresponding to the noble gas at the end of the corresponding long periodcorresponding long periodcorresponding long period.corresponding long period.

•• There are many exceptions to the 18There are many exceptions to the 18--electron rule which will be electron rule which will be explained by MOexplained by MO--theoretical considerations.theoretical considerations.

16.3 Scope of the 16/18-electron rule for d-block organometallic compounds



Usually less than 18 e- Usually 18 e- 16 or 18 e-

Sc Ti V Cr Mn Fe Co NiY Zr Nb Mo Tc Ru Rh PdLa Hf Ta W Re Os Ir Pt

16

18 Electron Rule18 Electron RuleOctahedral Complex Including Octahedral Complex Including ππ--BondingBonding

4p

t1u*

T1ut2g* (π*)

T2

•• Strong Strong ππ--bonding bonding interaction with COinteraction with CO

Eg

T1u

Eg

t2g (π)

3d

4s

4pa1g*

eg*

T2g

T2g

A1g


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK d-metal_31

A1g1u

Cr(CO)6Cr 6 CO

t1u

eg

a1g

18 Electron Rule18 Electron RuleOctahedral Complex Cr(CO)Octahedral Complex Cr(CO)66

•• CO is a CO is a σσ--donor, raising the donor, raising the eegg orbitals in E and making them considerably orbitals in E and making them considerably antianti--bondingbonding..

•• CO is a strong CO is a strong ππ--acceptor, lowering the acceptor, lowering the tt2g2g orbitals in E and making them orbitals in E and making them bondingbonding..

Ligands that are both, strong Ligands that are both, strong σσ--donors and donors and ππ--acceptors are most efficient in acceptors are most efficient in forcing adherence to the 18forcing adherence to the 18--electron ruleelectron rule..

Exception:Exception: [Zn(en)3]2+ is a 22 eis a 22 e-- complex!complex!



ZnN

NN

NN

N en is a weaker en is a weaker σσ--donor than CO and hence donor than CO and hence eeggorbitals are not sufficiently antiorbitals are not sufficiently anti--bonding to bonding to cause destabilizationcause destabilization

=>=> 4 4 ee-- in in eegg orbitalsorbitals and stable!and stable!

17

Square Planar 16 Electron ComplexesSquare Planar 16 Electron Complexes

ddxx22--yy22 is strongly antiis strongly anti--bonding (pointing directly towards the 4 ligands)bonding (pointing directly towards the 4 ligands)

Very important class of complexes, especially in homogeneous catalysisVery important class of complexes, especially in homogeneous catalysis

•• Square planar 16 Square planar 16 ee-- complexes of group 9 and 10, particularly for heavier complexes of group 9 and 10, particularly for heavier elements elements Rh(I)Rh(I),, Ir(I)Ir(I),, Pd(II)Pd(II),, Pt(II)Pt(II)

IrCl

PPh3OC

Ph3P IrIr 9 e9 e--

ClCl 1 e1 e--

COCO 2 e2 e--

2 Ph3P 4 ee-- =>=> 16 e16 e--Vaska’s complexVaska’s complex



RhCl

PPh3Ph3P

Ph3P

Wilkinson’s complexWilkinson’s complex

RhRh 9 e9 e--

ClCl 1 e1 e--

3 Ph3P 6 ee-- =>=> 16 e16 e--

Exceptions from the 18/16 Electron RuleExceptions from the 18/16 Electron Rule

•• Exceptions are common on the left side of the dExceptions are common on the left side of the d--blockblock

•• Steric and electronic factors are in competitionSteric and electronic factors are in competition

VC

CC

C

C

C

O

O

O

OO

OW

CH3

H3CH3C

CH3

CH3

CH3

17 e17 e-- 12 e12 e--

C C CO O O



Cr

OCCO

PPh3

17 e17 e--

steric bulk of PPhsteric bulk of PPh3 3 prevents prevents coordination of add. ligandcoordination of add. ligand

Cr Cr

C

CC C

C

OOO

18 e18 e--

long Crlong Cr--Cr bondCr bond

18

Typical Coordination GeometriesTypical Coordination Geometries

tetrahedral trigonalbipyramidal

octahedral

squarepyramidal

squareplanar

bipyramidal



geometry determined by electronic (crystal / ligand field)and steric (interligand repulsion) factors

geometric constraints (e.g multidentate or stericallydemanding ligands) can lead to significant distortions

••

••

Hessen/Elsevier

dd--Metal ComplexesMetal ComplexesSome Common Ligand FieldsSome Common Ligand Fields



•• Splitting diagrams referred to a common barycenterSplitting diagrams referred to a common barycenter

•• Splitting with respect to Splitting with respect to ΔO

squaresquareplanarplanar

trigonaltrigonalbipyramidalbipyramidal

squaresquarepyramidalpyramidal

octahedraloctahedral pentagonalpentagonalbipyramidalbipyramidal

squaresquareantiprismaticantiprismatic

19

dd--Metal ComplexesMetal Complexesππ--Bonding, Donor & Acceptor LigandsBonding, Donor & Acceptor Ligands

metal ligands metal ligands

ππ--acceptor ligands increase acceptor ligands increase ΔO

g g



ππ--donor ligands decrease donor ligands decrease ΔO

dd--Metal CarbonylsMetal Carbonyls

•• Homoleptic carbonyl complexes M(CO)Homoleptic carbonyl complexes M(CO)nn exist of most of the dexist of most of the d--metalsmetals

Simple carbonyls of Pd and Pt are unstable and exist only at low TSimple carbonyls of Pd and Pt are unstable and exist only at low TSimple carbonyls of Pd and Pt are unstable and exist only at low TSimple carbonyls of Pd and Pt are unstable and exist only at low T

No sNo simple carbonyls are known for Cu, Ag, Au and group 3 (Sc, Y, La)imple carbonyls are known for Cu, Ag, Au and group 3 (Sc, Y, La)

Carbonyl complexes are very important precursors for other Carbonyl complexes are very important precursors for other organometallic compoundsorganometallic compounds



organometallic compoundsorganometallic compounds

Carbonyl complexes are used in organic synthesis and catalysisCarbonyl complexes are used in organic synthesis and catalysis

20

MO’s of Carbon MonoxideMO’s of Carbon Monoxide



•• HOMO has HOMO has σσ symmetrysymmetry and point away from C in the COand point away from C in the CO--axisaxis=>=> forms forms σσ--donordonor bonds with the metalbonds with the metal

•• LUMO’s are LUMO’s are ππ* orbitals which play a crucial role in overlap with t* orbitals which play a crucial role in overlap with t2g2g metal metal orbitalsorbitals=>=> CO acts as CO acts as strong strong ππ--acceptoracceptor

MO’s of Carbon MonoxideMO’s of Carbon Monoxide



21

MO’s of Carbonyl ComplexesMO’s of Carbonyl ComplexesBond CharacteristicsBond Characteristics

emptyemptyoccupiedoccupied emptyempty

σσ--donordonor ππ--acceptoracceptor

occupiedoccupied



pp

Types of CO Binding ModesTypes of CO Binding Modes

C

OC

O

O



σσ--donordonor

M M

ππ--acceptoracceptor

M MM M

C

22

Types of CO Binding ModesTypes of CO Binding Modes

compound ν CO / cm -1Influence of Influence of

•• Electron poor metal center = competing Electron poor metal center = competing ππ--acceptor ligandsacceptor ligands=>=> reduced bond reduced bond length (stronger Clength (stronger C≡≡O) = higher O) = higher νCO

•• Electron rich metal center = strong Electron rich metal center = strong σσ--donor ligandsdonor ligands=>=> increased bond increased bond length (weaker Clength (weaker C≡≡O) = decreased O) = decreased νCO



CO (g) 2143[M n(CO)6]+ 2090Cr(CO)6 2000[V(CO)6]- 1860[Ti(CO )6]2- 1750Fe2(CO )9 2082, 2019, 1829

coordination and coordination and charge on charge on νCO

Fe

C

CC

Fe

C

CC

C

C

CO

O

OOO

O

O

O

O

Related Related ππ--Acceptor LigandsAcceptor Ligands

C N- < N N < C NR < C O < C S < N O+

•• Ligands isoelectronic with CO sorted by increasing Ligands isoelectronic with CO sorted by increasing ππ--acceptor strengthacceptor strength

νCO can be used to determine ππ--acceptor strengthacceptor strength

i d d h CO t tt-- νCO is decreased when CO acts as a ππ--acceptoracceptor

-- other other ππ--acceptor ligands cause acceptor ligands cause νCO to increase

- donor ligands cause νCO to decreased

•• CNCN-- and NOand NO++ significantly differ from COsignificantly differ from CO

-- CNCN-- is a good is a good σσ--donor and a weak donor and a weak ππ--acceptoracceptor

-- NONO++ is very strongly eis very strongly e-- withdrawingwithdrawing



-- NONO is very strongly eis very strongly e withdrawingwithdrawing

linear coordination,linear coordination,neutral 3 eneutral 3 e-- ligand ligand

bent coordination,bent coordination,as NOas NO--, 1 e, 1 e-- ligand ligand

23

Related Related ππ--Acceptor LigandsAcceptor Ligands•• The other ligands in the series NThe other ligands in the series N22, NCR, and CS preferably form complexes , NCR, and CS preferably form complexes

with metals in low oxidation stateswith metals in low oxidation states

•• SOSO22 is a fairly strong is a fairly strong ππ--acceptoracceptor

σσ--donor, donor, ππ--acceptor ligandacceptor ligand σσ--donation to the SOdonation to the SO22 ligandligandfound with found with ee-- rich metal centers, rich metal centers, SOSO22 acts as Lewis acid acts as Lewis acid

PFPF h blh bl t h t t COt h t t CO



•• PFPF33 has comparable has comparable ππ--acceptor character to COacceptor character to CO

•• P(OR)P(OR)33 ligands are somewhat weaker ligands are somewhat weaker ππ--acceptors, while PHacceptors, while PH33 and alkyl phosphines and alkyl phosphines are stronger are stronger σσ--donorsdonors

Transition Metal AlkylsTransition Metal Alkyls

σ-interactionpolar M-Cbond

M Cδ-δ+

H H

Electron-deficienttransition-metal alkyls: agostic interactions

bond

H HH H H H



CH

H

H

non-agosticα-agosticβ-agostic

M CC

H

H

H

HM

CC

H

HH

MC

C

H

H

H

Hessen/Elsevier

24

Carbenes and Metal AlkylidenesCarbenes and Metal AlkylidenesC

RNR2M

R singlettriplet

M CRR

NR2

R

R

NR

ggroundstate

tripletgroundstate

R

R

R

R

NR2



carbene

nucleophilic vs electrophilic

R

R

R

R

R

NR2

NR2

R

Hessen/Elsevier

Fischer carbenesFischer carbenes

πM C σM

•• singlet ground state singlet ground state ((HeteroatomsHeteroatoms))

•• Late(r) transition metals Late(r) transition metals with lower oxidation stateswith lower oxidation states(donation of electrons)(donation of electrons)

σ

π

σ

M



( )( )–– carbene is considered neutralcarbene is considered neutral

25

Schrock Carbenes (Alkylidenes)Schrock Carbenes (Alkylidenes)

•• ”Conventional" M=C bond:”Conventional" M=C bond:–– both both σσ en en ππ are covalent,are covalent,

expected polarization Mexpected polarization Md+d+--CCdd--

•• Triplet ground stateTriplet ground state

M σ

•• Triplet ground stateTriplet ground state•• Early transition metals with Early transition metals with

high oxidation stateshigh oxidation states–– Carbene is formally CCarbene is formally C22--

•• Carbene C is nucleophilicCarbene C is nucleophilic

πM

NMe2



Ta

NMe2

Cl

ClC

H

t-Bu

H2O CH

t-BuH

H

Metal Alkylidene BondsMetal Alkylidene Bonds•• electrophilic Fischer carbenes react with a nucleophileselectrophilic Fischer carbenes react with a nucleophiles

(CO)5Cr COMe

Ph+ :NHR2 (CO)5Cr C

NR2

Ph(CO)5Cr C

OMe

Ph

NHR2 + MeOH

Schrock Carbenes

•• Early transition metal carbenesEarly transition metal carbenes•• filled carbon pfilled carbon pzz orbital lower inorbital lower in

energy than denergy than d--ππ orbitalsorbitals=>=> Schrock carbene C is nucleophilicSchrock carbene C is nucleophilic



•• Schrock carbenes are catalysts for the alkene metathesis reactionSchrock carbenes are catalysts for the alkene metathesis reaction

TaClCl

CC

H+ Ta

ClClCCH

CH2

CMe3

H2

TaClCl

CH2 +H

26

Bonding SituationBonding SituationDewarDewar--ChattChatt--Duncanson ModelDuncanson Model

Transition Metal Transition Metal -- Alkene ComplexesAlkene Complexes

MC

CM

C

C

σσ--bondbond ππ--backbondbackbond



emptyemptydd--orbitalorbital

filled filled ethylene ethylene ππ--orbitalorbital

filled filled dd--orbitalorbital

empty empty ethylene ethylene ππ* orbital* orbital

Metal Alkene BondsMetal Alkene BondsDewarDewar--ChattChatt--Duncanson ModelDuncanson Model

•• Donation of eDonation of e-- density from a filled density from a filled ππ--MOMOof the alkene into a vacant metal of the alkene into a vacant metal σσ--orbital.orbital.

•• Acceptance of eAcceptance of e-- density from a filled density from a filled



pp yymetal dmetal dππ orbital into the vacant orbital into the vacant ππ**--MO MO of the alkene.of the alkene.

Organomet_52

27

Metal Alkene BondsMetal Alkene BondsBonding ModesBonding Modes

•• Depending on the electron density in both, the metal and the alkene, the Depending on the electron density in both, the metal and the alkene, the actual situation will lie between two extremesactual situation will lie between two extremes



-- very every e-- rich metal fragmentsrich metal fragments-- strongly estrongly e-- withdrawing withdrawing

substituents on the alkenesubstituents on the alkene

-- normal situation for most alkenesnormal situation for most alkenes

Metal Alkene BondsMetal Alkene BondsBonding ModesBonding Modes

•• The conformation with respect to the metalThe conformation with respect to the metal--alkene bond depends on the alkene bond depends on the metal fragmentmetal fragment

ML

L

coordination no.: 3coordination no.: 316 valence e16 valence e--

LL22M(alkene)M(alkene)

ML

LL



L

M

L

LL





•• ExamplesExamples(PPh(PPh33))22Ni(CNi(C22HH44)) K[PtCl K[PtCl 33(C(C22HH44)])] (PPh(PPh33))22IrBr(CO)TCNEIrBr(CO)TCNEPt(CPt(C22HH44))33 TCNE = tetracyanoetheneTCNE = tetracyanoethene

28

Metal Allyl BondsMetal Allyl BondsBonding ModesBonding Modes

Fe

OCOC

HH

HH

Pd ClCl

Pd NiL

X

HH

ηη11-- coordinationcoordination ηη33-- coordinationcoordination ηη11-- ηη22-- coordinationcoordination

3 H3H3

•• SynSyn and and antianti protons can be distinguished in protons can be distinguished in 11HH--NMR spectrumNMR spectrum•• Dynamic behavior (isomerization) on the NMR timeDynamic behavior (isomerization) on the NMR time--scale often leads to scale often leads to

averaged signalsaveraged signals



M

H

H

H3

HH

H2

H1

H2

H1

MH1

H2

H1

H2

Mantianti

synsyn

antianti

synsyn

•• Allyl metal complexes are important intermediates and metalAllyl metal complexes are important intermediates and metal--precursors precursors in catalytic reactionsin catalytic reactions

Metal Allyl BindingMetal Allyl Binding

ligandligandAA

σσ--bondsbonds ππ--bondsbonds

BB

ss ppyyppxx

ψψ11 ψψ22 ψψ33AA22

metalmetal

BB11



ddzz22

ppzz

ddyzyzddxzxz

see also extra information H16_7 allyl_radicalsee also extra information H16_7 allyl_radical

29

Metal Allyl BondsMetal Allyl BondsSynthesisSynthesis

Fe

OC COCO

HClFe Cl

OC CO

•• protonation of 1,3protonation of 1,3--diene complexesdiene complexes

OC CO OC CO

MgBr2 + NiCl2 Ni + 2 MgBrCl

•• reaction of metal halides with an allylreaction of metal halides with an allyl--Grignard reagentGrignard reagent

X + Pd(PPh3)4 PdX(PPh3)2

•• allylic substitution reactionsallylic substitution reactions



PdX(PPh3)2

X = OAc, OCORO

HCo(CO)4 +- CO

+Co(CO)3Co(CO)3

•• reaction of a metalreaction of a metal--hydride with a 1,3hydride with a 1,3--dienediene

Pd ClCl

PdDMSO

PdDMSOCl

DMSO2

Dynamic NMR BehaviorDynamic NMR Behavior

11H NMR spectrum of [(allyl)PdCl]H NMR spectrum of [(allyl)PdCl]22(d(d66 DMSO 140DMSO 140°°C 200 MHz)C 200 MHz)

11H NMR spectrum of [(allyl)PdCl]H NMR spectrum of [(allyl)PdCl]22(CDCl(CDCl33, 25, 25°°C, 200 MHz)C, 200 MHz)

(d(d66--DMSO, 140DMSO, 140 C, 200 MHz)C, 200 MHz)

HH1,21,2

•• A4X patternHH11HH22

HH33

H1

H2

H3

H1

H2

M

•• typical A2M2X pattern ofη3- bound allyl ligand



5.8 5.4 5.0 4.6 4.2 3.8 3.4 5.8 5.4 5.0 4.6 4.2 3.8 3.4 3.0 ppm3.0 ppm

HH33

5.8 5.4 5.0 4.6 4.2 3.8 3.4 5.8 5.4 5.0 4.6 4.2 3.8 3.4 3.0 ppm3.0 ppm

30










LLn-1M

HH

YYoxidative additionoxidative addition

++ HHYY- L

Ln-2MHH

YY

R

-- LL

YY

MMLLnn MMLLnn--11


ν = 18, 16ν = 18, 16 ν = 16, 14ν = 16, 14

ν = 18, 16ν = 18, 16

ν = 16, 14ν = 16, 14


associationassociationν 18 16ν 18 16



+ L RLn-2M

YY

RHH

RYY

HH

ν = 16, 14ν = 16, 14

ν = 18, 16ν = 18, 16reductive eliminationreductive elimination


ν = 18, 16ν = 18, 16

Catgen_sw1

31

Transition metalTransition metal

Factors Controlling Activity and SelectivityFactors Controlling Activity and Selectivityin a Metal Complexin a Metal Complex

R

•• e--configuration (d0-d10)•• orbital symmetry•• number of coordination sites•• ion or atom radius•• ionic or neutral•• nature of counter ions

LigandsLigands•• donor / acceptor properties•• dissociation constant•• space filling (cone angle)•• chelate effect•• bite angle•• symmetry



ML

L

R

SubstrateSubstrate•• in principle like ligands

Catgen_sw2

R3

Tolman’s Cone AngleTolman’s Cone AngleSteric Effects of Monodentate LigandsSteric Effects of Monodentate Ligands

°2.28 A Θ1/2Θ = Σ Θi / 2

3

2/3

P

R1 R2

Chadwick A. Tolman



C. A. Tolman, Chem. Rev. 1977, 77, 313-348.

React_mech_37

•• Steric crowding favors dissociative activation because in this way the Steric crowding favors dissociative activation because in this way the formation of the activated complex can relief strain.formation of the activated complex can relief strain.

Θ = Σ Θi / 2i=1

2/3

metal atommetal atom

last change: 090909

32

Tolman’s Cone AngleTolman’s Cone AngleChelating LigandsChelating Ligands

β

Θ


P

R2

R1 R1

R2

P



C. A. Tolman, W. C. Seidel, L. W. Gosser, J. Am. Chem. Soc. 1974, 96, 53-60.


Catgen_sw63

Ligand Θ / ° Ligand Θ / °CH3 90 P(OiPr)3 130

Tolman’s Cone AngleTolman’s Cone AngleMonodentate LigandsMonodentate Ligands

CO 95 η5-C5H5 (Cp) 136Cl, Et 102 PEt3 137PF3 104 P(OoTol)3 141Br, Ph 105 PPh3 145I, P(OCH3)3 107 P(iPr)3 160P(CH3)3 118 C5(CH3)5 (Cp*) 165tBu 126 PCy3 170



Bu 126 PCy3 170P(OPh)3 128 P(tBu)3 182

React_mech_38

C. A. Tolman, Chem. Rev. 1977, 77, 313-348.L. Stahl, R. D. Ernst, J. Am. Chem. Soc. 1987, 109, 5673.

•• Substitution reactions are commonly dominated by Substitution reactions are commonly dominated by steric effectssteric effects ((ΘΘ) and not ) and not by by electronic effectselectronic effects ((pKpKaa).).

33

Ligand Steric InfluenceLigand Steric Influence•• Steric bulk increases the rate of dissociative processes.Steric bulk increases the rate of dissociative processes.

NiL4 NiL3 + L

Cone angle Cone angle ΘΘ and Kand KDD for some Ni complexesfor some Ni complexes

C. A. Tolman, Chem. Rev. 1977, 77, 313-348.

L Θ /° KD

PMe3 118 < 10-9

PEt3 132 1.2x10-5

PMePh2 137 5.0x10-2

PPh3 145 largePtBu3 182 largein benzene at 25°C



In extreme cases even unusual electron configurations can be stabilized.In extreme cases even unusual electron configurations can be stabilized.

NiL4 NiL3 + L NiL2 + 2 Lνν = 16 e= 16 e--νν = 18 e= 18 e-- νν = 14 e= 14 e--

Cy3P Ni PCy3e.g.e.g.

Tolman’s Cone AngleTolman’s Cone AngleProblemsProblems

•• different conformations of substituentsdifferent conformations of substituents

°2.28 A

•• very bulky ligandsvery bulky ligands

•• local space at the metallocal space at the metal

•• chelating ligandschelating ligands•• flexibility



tan α = h / dΘ = 180 + 2 α

αh

d

Catgen_sw66

34

Ligand Electronic PropertiesLigand Electronic PropertiesTolman’s Tolman’s χχ--Value,Value,

νCO = 2056.1 + χi [cm-1]Σ3

i=1LNi(CO)3 {ν0 = P(tBu)3Ni(CO)3}TolmanTolman:: forfor

QUALE (Q tit ti A l i f Li d Eff t )QUALE (Q tit ti A l i f Li d Eff t )

group 1group 1:: σσ--donor ligandsdonor ligandsgroup 2group 2:: σσ--donor/ donor/ ππ--acceptoracceptor

QUALE (Quantitative Analysis of Ligand Effects)QUALE (Quantitative Analysis of Ligand Effects)

1940

1950

1960

group 2group 2ν CO

/cm

-1

GieringGiering::CpFe(COMe)(CO)L


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK Catgen_sw22

ligandsligands

A.L. Fernandez, C. Reyes, A. Prock, W.P. Giering,J. Chem. Soc., Perkin Trans. 2, 2000, 1033-1041.M.M. Rahman, H.-Y. Liu, K. Eriks, A. Prock, W.P. Giering, Organometallics, 8, 1-7.C. A. Tolman, Chem. Rev. 1977, 77, 313-348.

1910

1920

1930

0.1 0.2 0.3 0.4 0.5 0.6

group 1group 1

E0/V

Organomet_22

Dimerization of PropeneDimerization of Propene+ +

[Ni-Kat.]

headhead--headhead headhead--tailtail tailtail--tailtail

n-Hexenes80

90%

2,3-Dimethylbutene2-Methylpentene

NiR3P

+

AlCl4-Cat. :

T = - 20°C p = 1 bar30

40

50

60

70

80



B. Bogdanovic, Adv. Organomet. Chem. 1979, 17, 105-140.

T 20 C , p 1 bar

PPh3 PMe3 PCy3iPr2PtBu-

0

10

20

- iPrPtBu2

Catgen_sw5

35

Dimerization of PropeneDimerization of PropeneTry to Explain Ligand Influences !Try to Explain Ligand Influences !

NiL

XH

CH3

H3C

NiNi--CC11 insertioninsertion



B. Bogdanovic, Adv. Organomet. Chem. 1979, 17, 105-140.G. Henrici-Olivé, S. Olivé, Top. Curr. Chem. 1976, 67, 107-127

NiNi--CC22 insertioninsertion

solutionsolution

VCH

*

OligoOligo-- and Cyclooligomerization of 1,3and Cyclooligomerization of 1,3--ButadieneButadieneLigand InfluencesLigand Influences

[ L'''Ni/R2NH ] [ Ni ]

[ L''Ni ]

[ L'Ni ]

1,5-COD

[ L'Ni ]

DVCB

Günther Wilke



P. Heimbach, P. W. Jolly, G. Wilke, Adv. Organomet. Chem. 1970, 8, 29.

1,3,6-OT ttt-1,5,9-CDT

L' = P(OCL' = P(OC66HH44--oo--Ph)Ph)3 , 3 , Θ = 152° ; L'' = P(Cy)L'' = P(Cy)3 , 3 , Θ = 170°; L''' = P(OEt)L''' = P(OEt)3 , 3 , Θ = 109°

Catgen_sw6

36

Mechanistic Routes to Different ProductsMechanistic Routes to Different ProductsTry to Explain Ligand Influences !Try to Explain Ligand Influences !

Ni[Ni] Ni Ni1,5-COD

VCH

*



G. Wilke, Angew. Chem. 1988, 100, 189.

ttt-1,5,9-CDToxidoxid. coupling. coupling

elem. react. stepselem. react. steps

solutionsolution

Selectivity Control by L/NiSelectivity Control by L/Ni--RatioRatio



L = PPhL = PPh33, T = 60, T = 60°°C, [Ni] = 32 mmol/lC, [Ni] = 32 mmol/l

P. Heimbach, H. Schenkluhn, Top. Curr. Chem. 1980, 92, 45.Catgen_sw7

37

Bulky LigandsBulky LigandsHeck Olefination ReactionHeck Olefination Reaction

OP

MeO

N

I+

[Pd(dba)2 / 2 L]

NEt3, CH3CN80°C, 45 min

PdL

Br

BrPd

L

catalystcatalystO

MeO

OP

O

A

Bonve

rsio

n [%

]on

vers

ion

[%]

40

60

80

100 TON up to 500.000TON up to 500.000



O O

O OPPd

PPd

(o-tol)2

(o-tol)2

C

Catgen_sw17

coco

0

20

PPh3

P(o-

tol) 3

P(O

Ph) 3 A B C

G.P.F. van Strijdonck, M.D.K. Boele, P.C.J. Kamer, J.G. de Vries, P. W.N.M. van Leeuwen, Eur. J. Inorg. Chem. 1999, 1073-1076.

Bulky Ligands in Bulky Ligands in Heck Olefination ReactionHeck Olefination ReactionI

+[Pd(dba)2 / 2 L]


P4a: L =4a: L = OP

MeO

N4b L4b LPd

L

Br

BrPd

L

P4a: L =4a: L = PO

MeO

N4b: L =4b: L = catalystcatalyst



38

I+

[Pd(dba)2 / 2 L]


Bulky Ligands in Bulky Ligands in Heck Olefination ReactionHeck Olefination Reaction

rate law:rate law: zero order in [iodobenzene]zero order in [iodobenzene] (0.10 (0.10 –– 2.0 M)2.0 M)zero order in [NEtzero order in [NEt33]] (0.16 (0.16 –– 2.5 M)2.5 M)first order in [alkene]first order in [alkene] ( 0 ( 0 –– 4.0 M)4.0 M)½ order in [Pd]½ order in [Pd] ( 0 ( 0 –– 4.0 mM)4.0 mM)



r = k[alkene][Pd]r = k[alkene][Pd]1/21/2

What does this mean ?What does this mean ?

Bulky LigandsBulky LigandsHeck Olefination ReactionHeck Olefination Reaction

[Pd-L] ArXB

HBX

catalyst resting statecatalyst resting state

PdX

XPd

L

Ar LAr

R

PdArLX

PdLX

H

Ar RPd

LX

Ar

H R

PdHLX

Ar

R

B



•• bulky ligands suppress formation of binuclear complexesbulky ligands suppress formation of binuclear complexes•• oxidative addition is NOT rate limiting oxidative addition is NOT rate limiting !!

very high TONvery high TON

H R

G.P.F. van Strijdonck, M.D.K. Boele, P.C.J. Kamer, J.G. de Vries, P. W.N.M. van Leeuwen, Eur. J. Inorg. Chem. 1999, 1073-1076.

r = kr = k22 KK1/21/2[alkene][Pd][alkene][Pd]1/21/2

39

Copolymerization of Ethene and COCopolymerization of Ethene and COEffects of Chelating LigandEffects of Chelating Ligand(PPh3)2PdX2

CH3OH+ CO

O

O

methylpropionatemethylpropionate> 98 %> 98 %

CH3OH

(DPPP)2PdX2

+ CO

O

O

Hn

alternating polyketonealternating polyketone> 99.9 %> 99.9 %

PPh2

PPh2

X = F3CSO3- ; DPPP :

COP 1 InsertionO

PP

OCPd

P

R

PdP

ORP

Eite DrentEite Drent



E. Drent, J. A. M. van Broekhoven, P. H. M. Budzelaar in Appl. Homog. Catal. with Organomet. Comp.(Eds.: B. Cornils, W. A. Herrmann) Vol. 1, VCH 1996, pp. 333-351.

PPd CO

R

P 1. Insertion

2. C2H4 PPd RPR

PPd CO

R

P

PPd

ORP

Catgen_sw10

Natural Bite Angle Natural Bite Angle ββnn of a Chelating Ligandof a Chelating Ligand

PP

PP

ββnn

d d MM--PP

d d RhRh--PP = 2.315 A= 2.315 A

d d NiNi--PP = 2.177 A= 2.177 A

°°°°



“The natural bite angle (βn) is defined as the preferred chelation angle determined only by ligand backbone constraints and not by metal valence angles.

The flexibility range is defined as the accessible range of bite angles within less than 3 kcal / mol excess strain energy from the calculated bite angle”.C. P. Casey, G. T. Whiteker, Isr. J. Chem. 1990, 30, 299-304.

Catgen_sw78

40

Flexibility Range of Xantphos LigandsFlexibility Range of Xantphos Ligands

SixantphosSixantphos

l mol

l mol

--11)) DPEphosDPEphos

O O

Si

mat

iona

l ene

rgy

(kca

lm

atio

nal e

nerg

y (k

cal

DPEphos

P P P P

Sixantphos



PP--RhRh--PP

ββnn = 108= 108°°

PP--RhRh--PP

ββnn = 101= 101°°

conf

orco

nfor

Catgen_sw79

Bite Angle Electronic EffectsBite Angle Electronic Effects

E [ e

V ]

E [ e

V ]

≈

πu

δg*

≈

2b1

4a1

2b2

PP

PPMM

δ δ

δg, πg

δg*

1b 1a

3a1

2a1, 2b2, 1a2

•• ββnn small =>small => nucleophilic character nucleophilic character

raised reduction potentialraised reduction potential

•• ββnn large =>large => electrophilic characterelectrophilic characterlower reduction potentiallower reduction potential

a large bite angle cana large bite angle can



S. Otsuka, J. Organomet. Chem. 1980, 200, 191.T. Yoshida, K. Tatsumi, S. Otsuka, Pure Appl. Chem. 1980, 52, 713.

z

x

y

LLPPttLL

x

zyPPtt

LL

LL

δu, δg 1b1, 1a1

Walsh diagram for d10 fragments

a large bite angle cana large bite angle can-- enhance the coordination of an olefinenhance the coordination of an olefin-- enhance reductive eliminationsenhance reductive eliminations

41

Bite Angle EffectsBite Angle EffectsRates of Reductive EliminationRates of Reductive Elimination

P

P

PPd

P

PPd

CN

TMSP P^P

NC CH TMS- NC-CH2TMS

100

1000

10000

log

k [s

-1]

91°

98°

•• acceleration by 104 !



J.E. Marcone, K.G. Moloy, J. Am. Chem. Soc. 1998, 120, 8527-8528.

1

10

dppe dppp diop

-

85°

Ligand Bite AnglesLigand Bite Angles

DPEphosDPEphosββnn = 102= 102°° (86(86--120120°°))

OPh2P PPh2

SixantphosSixantphosββnn = 109= 109°° (93(93--130)130)

OPh2P PPh2

Si

Ph2P PPh2

BISBIBISBIββnn = 123= 123°° (101(101--148148°°))

PPh2Ph2PTRANSphosTRANSphosββnn = 111.2= 111.2°° ββnn (( )) ββnn (( ))ββnn (( ))ββnn 111.2 111.2

ThixantphosThixantphosββnn = 110= 110°° (96(96--130130°°))

OPh2P PPh2

S

XantphosXantphosββnn = 111= 111°° (97(97--133133°°))

OPh2P PPh2

O O

Ph2P PPh2

DIOPDIOPββnn = 98= 98°° (90(90--120120°°))

BINAPBINAPββnn = 92= 92°°

Ph2P PPh2

BINAPOBINAPOββnn = 105= 105°°

O OPPh2Ph2P


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK M3P-sw13

Ph2P PPh2DPPEDPPE

ββnn = 78= 78°°

OPPh2Ph2P

DBFphosDBFphosββnn = 131= 131°° (117(117--147)147)

DPPPDPPPββnn = 86= 86°°

Ph2P PPh2

DPPBDPPBββnn = 99= 99°°

Ph2P PPh2

P.W.M.N. van Leeuwen, P.C.J. Kamer, J.N.H. Reek, P. Dierkes, Chem. Rev. 2000, 100, 2741-2769.

42

Large Bite Angle DiphosphinesLarge Bite Angle Diphosphines

PP PPMM

rigid backbonerigid backbone

large bite anglelarge bite angle ββnn

O

X RR

PAr2PAr2

X R Ar βn** [°]

1a H, H H Ph 1051b SiMe2 H Ph 1121c S Me Ph 113


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK HCN-sw5

Xantphos ligandsXantphos ligands

1

1d CMe2 H Ph 1141e CMe2 H 3,5-(CF3)2Ph 1171f - H Ph 140

* calculated based on Ni* calculated based on Ni--P = 2.177 AP = 2.177 A°°

Mirko Kranenburg, Organometallics 1995, 14, 3081-3089.

XX--Ray Structures of Xantphos LigandsRay Structures of Xantphos Ligands

OO PPPP

SiSi

OOPPPP



W. Goertz, W. Keim, D. Vogt, U. Englert, Maarten D.K. Boele, L.A. van der Veen, P.C.J. Kamer, P.W.N.M. van Leeuwen, J. Chem. Soc., Dalton Trans. 1998, 2981-2988.

SixantphosSixantphosββnn = 109= 109°° (93(93--130)130)

SS

ThixantphosThixantphosββnn = 110= 110°° (96(96--130130°°))

43

Hydroformylation of 1Hydroformylation of 1--OcteneOctene

50

60109°

112° 123°

+ CO/H2 CHOCHO

+[Rh-cat.]

10

20

30

40

l/b

l/b --

ratio

ratio

84°

102°

108°

131°

Piet van Leeuwen



M. Kranenburg, Y.E.M. van der Burgt, P.C.J. Kamer, P.W.N.M. van Leeuwen, K. Goubitz, J. Fraanje, Organometallics, 1995, 14, 3081-3089.

0

DPP

E

DPE

phos

Sixa

nt

Thix

ant

Xant

phos

BIS

BI

DB

Fpho

sCatgen_sw14

T = 40°C, p = 10 bar CO/H2 (1:1), substrate/Rh = 674, L/Rh = 2.2, [Rh] = 1.78 mM

Counterion Effects and Hemilabile LigandsCounterion Effects and Hemilabile LigandsHydrovinylation of StyreneHydrovinylation of Styrene

+[(η3-allyl)NiBr]2 / L*

AgXCH2Cl2, - 45°C, 1.5 h

* + + homo-oligomers+ higher co-oligomers

nver

sion

[%]

nver

sion

[%]

40

60

80

100 AB

P

A

P

O



M. Nandi, J. Jin, T. V. RajanBabu, J. Am. Chem. Soc., 1999, 121, 9899-9900.

con

con

0

20

40

OTf ClO4 NTf2 SbF6 B(ArF)4

P

B

Catgen_sw86

44

Simulated StructureSimulated StructureWeakly Coordinating Anion as Bulky LigandWeakly Coordinating Anion as Bulky Ligand

H

XOP

Ni

**

free volumefree volumearound Ni at 2.2 Åaround Ni at 2.2 Å

styrenestyrene

PP

NN



Coordination of the olefin at the metal is supposed to be the enantioselective stepCoordination of the olefin at the metal is supposed to be the enantioselective step

HYVHYV--swsw8787

around Ni at 2.2 Åaround Ni at 2.2 Å

K. Angermund, A. Eckerle, F. Lutz, K. Angermund, A. Eckerle, F. Lutz, Z. Naturforsch. Z. Naturforsch. 19951995, , 50b50b, 488., 488.

Chirality in NatureChirality in Nature

Snail (Snail (Helix pomatiaHelix pomatia))

Appears as right and left handed form in a ratio of 5000 15000:1.

Colored snail (Colored snail (Liguus virgeneusLiguus virgeneus))

Like most snails right winding; only mutants occasionally have the opposite winding.



Field bind weed (Field bind weed (Convolvulus arvensisConvolvulus arvensis))

As most climbing plants, it only grows right winding.

Asymm-sw3

45

Different Effect of EnantiomersDifferent Effect of Enantiomers

odor of lemonodor of lemon odor of orangesodor of oranges

LimoneneLimoneneS

CH3R

CH3

AsparagineAsparagine

bitter tastebitter taste

S H2N OHO

O

NH2

sweet tastesweet taste

RNH2

O

O

NH2

HO

odor of lemonodor of lemon odor of orangesodor of oranges

PropranololPropranololS

OOH

NH

CH3

CH3

R

OOH

NH

H3C

CH3



betabeta--blockerblocker

S

causes liver damagecauses liver damage

R

EthambutolEthambutol

drug for tuberculosis treatmentdrug for tuberculosis treatment

S,SH3C

N

OH

N

OH

CH3

causes blindnesscauses blindness

R,RCH3

N

HO

N

HO

H3C

Asymm-sw5

Use of Chiral Compounds Use of Chiral Compounds •• Food additivesFood additives•• PharmaceuticalsPharmaceuticals•• Feed additivesFeed additives

The different physiological effect of enantiomers must The different physiological effect of enantiomers must be taken into account!be taken into account!

•• Feed additivesFeed additives•• Agro chemicalsAgro chemicals



The "The "wrongwrong" enantiomer can be:" enantiomer can be:•• ineffective,ineffective,•• poisonouspoisonous•• of opposite effect.of opposite effect.

Asymm-sw6

46

•• The main markets for chiral technology and chiral The main markets for chiral technology and chiral intermediates are:intermediates are:

Chiral MoleculesChiral MoleculesMarket SegmentationMarket Segmentation

-- PharmaceuticalsPharmaceuticals (81 %)(81 %)

-- AgrochemicalsAgrochemicals (14 %)(14 %)

-- Flavors and fragrancesFlavors and fragrances (5 %)(5 %)

-- Material science, polymers, liquid crystals and veterinary medicinesMaterial science, polymers, liquid crystals and veterinary medicines

F & F Materials



Source: Frost & Sullivan, 2001

5%Agro14%

0%

Pharma81%

Asymmetric SynthesisAsymmetric Synthesis•• classical synthesisclassical synthesis

+ +

reagentreagent product 1:1product 1:1substratesubstrate

•• stereoselective synthesisstereoselective synthesis



chiral auxiliarychiral auxiliary

reagentreagent

+

substratesubstrate product, left handed onlyproduct, left handed only

Asymm-sw7

47

Conversion of a Substrate Using aConversion of a Substrate Using aChiral CatalystChiral Catalyst

H Hchiral

t l tH H

(Si)(Si)

CH3

((SS))

catalyst

chiral ligand

H+

((RR))



A chiral catalystchiral catalyst favors one face of the substrateOneOne product enantiomerenantiomer is formed predominantlypredominantly

Asymm-sw13

Asymmetric SynthesisAsymmetric Synthesis

*

HH

*O OHHOHH

HH

sisi--half spacehalf spaceSSRR

rere--half spacehalf space

ΔΔ

G

[kJm

ol-1

]#

6

8

10

12

ΔG# ΔG#

ΔΔG#



0

2

4

0 20 40 60 80 100ee [%]

ΔGR ΔGS

48









heterogeneous homogeneous biocatalysis

Comparison of Catalytic PrinciplesComparison of Catalytic Principles

Advantages and disadvantages of heterogeneous, homogeneous, Advantages and disadvantages of heterogeneous, homogeneous, and bio catalysisand bio catalysis

heterogeneous homogeneous biocatalysisg g y

Conditions generally harsh mild mild

Activity changing high i.g. very high

Selectivity changing high i.g. very high

Catalyst life-time high changing i.g. low

Catalyst recycling solved expensive expensive

Sensitivity agains poisons high low high

Diffusion problems possible none only whole cells

g g y

Conditions generally harsh mild mild

Activity changing high i.g. very high

Selectivity changing high i.g. very high

Catalyst life-time high changing i.g. low

Catalyst recycling solved expensive expensive

Sensitivity agains poisons high low high





Mechanistic understanding low medium to good medium

Catalysis_07


Mechanistic understanding low medium to good medium

49

Homogeneous CatalysisHomogeneous Catalysis

Process Catalyst Capacity / 1000 t/a

Homogeneous catalytic processes in industryHomogeneous catalytic processes in industry

Hydroformylation HRh(CO)n(PR3)m 3690

HCo(CO)n(PR3)m 2445

Hydrocyanation (DuPont) Ni[P(OR3)]4 ∼1000

Ethene-Oligomerization (SHOP) Ni(P^O)-chelate complex 870

Acetic acid (Eastman Kodak) HRhI2(CO)2 / HI / CH3I 1200

Acetic acid anhydride (Tennessee-Eastman) HRhI2(CO)2 / HI / CH3I 227

Metolachlor (Novartis) [Ir(ferrocenyldiphosphine]I / H2SO4 10



Citronellal (Takasago) [Rh(binap)(cod)]BF4 1,5

Indenoxide (Merck) chiral Mn(salen)-complex 600 kg scale

Glycidol (ARCO, SIPSY) Ti(OiPr)4 / diethyl tartrate several tons









50

Homogeneous HydrogenationHomogeneous Hydrogenation•• Wilkinson’s catalyst 1965 Wilkinson’s catalyst 1965 RhCl(PPhRhCl(PPh33))33

1st homogeneous hydrogenation catalyst1st homogeneous hydrogenation catalyst

Synthesis of the catalystSynthesis of the catalystEtOH

RhCl3 * 3 H2O + exc. PPh3

EtOH

80°CRhCl(PPh3)3 + 2 HCl + Ph3P=O

dd6644

IIIIII II

Reversible coordination of etheneReversible coordination of ethene

RhCl(PPh3)3 +20°C

trans-RhCl(C2H4)(PPh3)2 + PPh3



R coordinates less by a factor of 2000coordinates less by a factor of 2000

Irreversible coordination of COIrreversible coordination of CO

RhCl(PPh3)3 + CO20°C

trans-RhCl(CO)(PPh3)2 + PPh3

e.g. decarbonylation of aldehydes can lead to the deactivation of the catalyste.g. decarbonylation of aldehydes can lead to the deactivation of the catalyst

Homogeneous HydrogenationHomogeneous Hydrogenation

oxidative additionreductiveelimination

H2

RhL

LCl

L

LLH

R

H H

RhL

H

R

LL

RhL

ClL

HL

RhL

ClL

H

H

H

liganddissociation

RhCl

LH

LR

H

RhCl

L

RHL

ligandassociation



alkenecoordinationR

RhL

ClL

H

R

H

migratoryinsertion

•• HH22 activation is the rate limiting stepactivation is the rate limiting step

51


Cp* La HR R

Lanthanocene hydride catalystsame transformation, very different cycle!

σ-bondmetathesis

Cp*2LaH

H δ+δ+

δ-

δ-Cp*2La

H

R

Cp*2La Holefincoordination



R

δ+ δ-

H2Cp*2La

R

H

migratoryinsertion

Hessen/Elsevier

•• The least substituted C=C bond is hydrogenated fastestThe least substituted C=C bond is hydrogenated fastest


R» » > »

•• For simple alkenes manly steric factors determine the reactivityFor simple alkenes manly steric factors determine the reactivity

terminal > internalcis > trans

hydrogenation is stereospecific hydrogenation is stereospecific ciscis



low tendency towards isomerizationlow tendency towards isomerization

tolerated functional groups:tolerated functional groups: COOH, COOR, CN, NO2, O

strongly coordinating strongly coordinating substratessubstrates inhibit:inhibit: NH2 COOH;

52

Asymmetric HydrogenationAsymmetric HydrogenationCOOR

NHAcMeO

OAc

H2

[Rh(dipamp)]+ NH2

COOH

HOOH

OMe

LL--DOPADOPA

•• Monsanto’s LMonsanto’s L--DOPA processDOPA processLL DOPA is an agent against Parkinson’s diseaseDOPA is an agent against Parkinson’s disease

P P

MeO

DIPAMP

+N

COOMeHN

MeOOC H +

RhS

SP

P*+

ArNHCOMe

COOMe+

LL--DOPA is an agent against Parkinson’s diseaseDOPA is an agent against Parkinson’s disease



+ RhP

P *ArOH3C

RhP

P* ArO CH3

kR kS

majormajordiastereomerdiastereomer

minorminordiastereomerdiastereomer

kS » kR

((SS))--product formed predominantlyproduct formed predominantly

NO

HNO N

OClO

[I (I) K t ]

Asymmetric Hydrogenation of IminesAsymmetric Hydrogenation of IminesApplication of Chiral Ferrocenyl Phosphines at CIBAApplication of Chiral Ferrocenyl Phosphines at CIBA

[Ir(I) Kat.]

((SS))--metolachlor, metolachlor, herbizideherbizideee = 80 %ee = 80 %

I (I) / li d / i did / HI (I) / li d / i did / H SOSOPchiral ligand



Ir(I) / ligand / iodide / HIr(I) / ligand / iodide / H22SOSO44substrate / Ir < 1 000 000substrate / Ir < 1 000 000

PPh2Fe2

g

H.-U. Blaser, H.-P. Buser, R. Häusel, H.-P. Jalett, F. Spindler, J. Organomet. Chem. 2001, 621, 34-38.H.-U. Blaser, M. Studer, Applied Catalysis A: General 1999, 189, 191-204.

Asymm_01

53

Other Chiral DiphosphinesOther Chiral DiphosphinesApplicationApplication

99 % e.e.100 bar H2

NEt3

Ru(BINAP)(RCO2)2

R R

O O

R R

OH O

PPh2

P

RR

R

NCH3 N

F

NO

OCO2H

OHOH

OHO ((R)-BINAP)Ru2+

H2 70 bar

Levofloxacin



PPh2

PPh2P

R

R

RR--DuPhosDuPhos SS--BINAPBINAP

A. Miyashita, …., R. Noyori,J. Am.Chem. Soc. 1980, 102, 7932.

M.J. Burk, J.E. Harlow,J. Am.Chem. Soc. 1992, 114, 6266.

Hessen/Elsevier

Phosphorus LigandsPhosphorus Ligandsfor Asymmetric Hydrogenationfor Asymmetric Hydrogenation

PCy2

PCy2

FeP

P

PPh2PPh2

O OPh2P PPh2P P

OMe

Josiphos

Spindler, Togni 1994

P

DuPHOS

Burk 1990

2

BINAP

Noyori 1980Kagan 1972

Ph2P PPh2

CHIRAPHOS

Bosnich 1977

MeO

Knowles 1972

PPhOOPh

P tBuPPh2



PPh2PPh2

BIPHEMP

Schmid 1988

OO

P OR*

Reetz 2000

OO

P N

Ph

Feringa 2000

PtBu

tBuHH

TangPhos

Zhang 2002

PPh2

Phanephos

Pye, Rossen 1997

54









HydroformylationHydroformylation

•• The hThe hydroformylation reaction was found by O. Roelen in 1938 during his ydroformylation reaction was found by O. Roelen in 1938 during his work on Fischerwork on Fischer Tropsch synthesisTropsch synthesis

R R

CHO

RCHO+

CO/H2

[catalyst]

work on Fischerwork on Fischer--Tropsch synthesisTropsch synthesis

Very important reaction for the production of softeners for plastics and Very important reaction for the production of softeners for plastics and detergent alcohols.detergent alcohols.

Bulky substituents increase the linearity of the product.Bulky substituents increase the linearity of the product.



Acceptor ligands increase the rate of the reaction by accelerating ligand and Acceptor ligands increase the rate of the reaction by accelerating ligand and CO dissociation and olefin coordination.CO dissociation and olefin coordination.Acceptor ligands increase the ratio of linear productAcceptor ligands increase the ratio of linear product..

55

Catalyst Co(CO)4H Co(PBu3)(CO)3H Rh(CO)4H Rh(TPP)3(CO)H Rh(TPPTS)3(CO)H

T 110-180°C 160-200°C 100-140°C 85-115°C 50-130°C

p 200-350 bar 30-100 bar 200-300 bar 15-20 bar 10-100 bar

Products aldehydes alcohols aldehydes aldehydes aldehydes

Industrial Hydroformylation Overview Industrial Hydroformylation Overview

l/b (propene) 80:20 88:12 50:50 92:8 95:5

Byproducts medium high low low low

Poisoning low medium high - high

Feed stocks C2-C20 Higher alkenes spec. alkenes,ethene

lower alkenes lower alkenes

Processes RuhrchemieBASFKuhlmann

Shell - LPO Ruhrchemie/RhônePoulenc



Separationcat./product

several distillation underincreasedpressure

- distillation phase separation

Catalystrecycling

several in residue - cat. remains inreactor

in aqueous phase

HydroformylationHydroformylation

Formation of the catalyst complexFormation of the catalyst complex

Co2(CO)8H2

2 HCo(CO)4•• Cobalt systems:Cobalt systems:

At high Rh concentration and low pressure there is an equilibrium between At high Rh concentration and low pressure there is an equilibrium between catalytically inactive dimeric species and the active hydride.catalytically inactive dimeric species and the active hydride.

(acac)Rh(CO)2

CO/H2 ; L

- Hacac

HRhCO

COLL•• Rhodium systems:Rhodium systems:



2 Rh

H

CO

COL

L+ H2

C

CRhL

L

LRhC

C L

O O

OO

cata yt ca y act e d e c spec es a d t e act e yd decata yt ca y act e d e c spec es a d t e act e yd de

56

Hydroformylation Hydroformylation (Cobalt(Cobalt--catalyzed)catalyzed)

ROR

COH H

H2

(CO)4Co Co(CO)4

ligandexchange

mechanism?

CO

CO- CO

H2

H

Co

COCO

COR

Co

CO

OCCO

CO

O R

H

Co

CO

OCCO

COexchange



COCO

COCO

Co

CO

OCCO

CO

R

migratoryinsertion

migratoryinsertion

Hessen/Elsevier

Hydroformylation Hydroformylation (Cobalt(Cobalt--catalyzed)catalyzed)

Sterically demanding phosphines increase linearity

PC20H41 P

(Shell Process)

Co-cat can hydroformylate internal alkenesto linear aldehydes



to linear aldehydes

- Fast isomerisation of the alkene

- Only conversion to aldehyde via primary alkyl

Hessen/Elsevier

57

HydroformylationHydroformylation•• In most cases CO or ligand In most cases CO or ligand

dissociation is the rate limiting dissociation is the rate limiting step, together with olefin step, together with olefin coordination.coordination.

liganddissociation

R

HRhCO

COLL

H LO R

CO

lk

ν = 18ν = 18

RhCOL

L

HRhCO

LL

RRh

H

COL

HLR

O

alkenecoordination

migratoryinsertion

oxidative addition

reductiveelimination

ν = 16ν = 16

ν = 18ν = 18



RhCO

COLL

RRhCOL

LRO

RhCOL

L R

CO

H2

ligandassociation

migratoryinsertion

ν = 18ν = 18

ν = 16ν = 16ν = 16ν = 16Type I rate law:Type I rate law:

r =k [H2][Rh]

[CO]-1

RhOCP

R

CHO

R

H

RhP

HydroformylationHydroformylationRegioselectivityRegioselectivity

Rh

CO

OCP R

RCHORh

CO

OCP

P

R

R

Rh

CO

PP

H

Rh

CO

PP

Linearity increases with Tolman cone angleLinearity increases with Tolman cone angle ΘΘ



Linearity increases with Tolman cone angle Linearity increases with Tolman cone angle ΘΘ

Linearity bulky phosphites > phosphines, BUT: Linearity bulky phosphites > phosphines, BUT:

For very large coneFor very large cone--angle angle Θ Θ only ONE P on Rh only ONE P on Rh fast but also isomerization (see table 6.4)fast but also isomerization (see table 6.4)

Hessen/Elsevier

58

HydroformylationHydroformylationRhodiumRhodium--PhosphitePhosphite

•• Among first ligands used in hydroformylation (apart from PPhAmong first ligands used in hydroformylation (apart from PPh33))

•• Large acceptorLarge acceptor--type ligands: lead to unstable catalysts HRh(CO)type ligands: lead to unstable catalysts HRh(CO)33(P);(P);these are extremely reactive. Only ONE Pthese are extremely reactive. Only ONE P--ligand on metal;ligand on metal;these are extremely reactive. Only ONE Pthese are extremely reactive. Only ONE P ligand on metal; ligand on metal; space limitationspace limitation

This complex may This complex may easily loose COeasily loose CO

OP

OO

R

R

H

Rh

CO

OCCO

P



•• Fast hydroformylation, also of 2Fast hydroformylation, also of 2--alkenes and other internal alkenes!alkenes and other internal alkenes!Extremely fast for 1Extremely fast for 1--alkenes; high linearity of product.alkenes; high linearity of product.

BUT: also isomerization of 1BUT: also isomerization of 1-- to 2to 2--alkenes alkenes branchedbranched

R Θ = 195Θ = 195οο

Hessen/Elsevier

HydroformylationHydroformylationRhodiumRhodium--PhosphinePhosphine

H H

•• Alkylphosphines: donors Alkylphosphines: donors stabilize Rhstabilize Rh--CO bond;CO bond;hence little COhence little CO--dissociation and very SLOW reaction dissociation and very SLOW reaction

•• Smaller (bidentate) arylphosphines give more stable catalysts;Smaller (bidentate) arylphosphines give more stable catalysts;these are less reactive, and give less linear product these are less reactive, and give less linear product (equil. right hand side)(equil. right hand side)

H

Rh

CO

OCP

P

H

Rh

P

OCCO

P



•• Larger (bidentate) arylphosphines, especially with high Larger (bidentate) arylphosphines, especially with high χχ--values give more linear product (equil. left hand side)values give more linear product (equil. left hand side)

Hessen/Elsevier

59

Ligand ConceptLigand ConceptChelating ligands possessing a rigid backboneChelating ligands possessing a rigid backbone

P Prigid backbone

(Xantphos(Xantphos--Ligands)Ligands)

P PM

Large bite angle βn

Ar

Ph

Ph

R

H

HSiMe2

X

H, H

βn[°]

102

108

DPEphos

SixantphosO

X RR


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK M3P-sw4

M. Kranenburg, Y.E.M. van der Burgt, P.C.J. Kamer, P.W.N.M. van Leeuwen, K. Goubitz, und J. Fraanje, Organometallics, 1995, 14, 3081.

Ph

Ph

Ph

H

H

Me

SiMe2

S

CMe2

108

109

112Xantphos

Thixantphos

Sixantphos

Xantphos-Ligands

OPAr2PAr2

Hydroformylation of 1Hydroformylation of 1--OcteneOctene

50

60109°

112° 123°

+ CO/H2 CHOCHO

+[Rh-cat.]

10

20

30

40

l/b

l/b --

ratio

ratio

84°

102°

108°

131°

Piet van Leeuwen



M. Kranenburg, Y.E.M. van der Burgt, P.C.J. Kamer, P.W.N.M. van Leeuwen, K. Goubitz, J. Fraanje, Organometallics, 1995, 14, 3081-3089.

0

DPP

E

DPE

phos

Sixa

nt

Thix

ant

Xant

phos

BIS

BI

DB

Fpho

s

Catgen_sw14

T = 40°C, p = 10 bar CO/H2 (1:1), substrate/Rh = 674, L/Rh = 2.2, [Rh] = 1.78 mM

60

+ CO / H2CHOUnion Carbide,

Rhodium + Phosphine

Catalyst-Recycling V

CO / H2

substrate

productreactor

flashdistillation

HRh(CO)(PPh3)3


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK Hydroform_05

make up purge(tars)

•• low CO pressure•• low temperature•• very hydridic character•• limited to light alkenes !

(volatile aldehydes)

stable in molten PPh3

+ CO / H2CHORuhrchemie/Rhône Poulenc,

Rhodium + Phosphinetwo Phase Process

Catalyst-Recycling VI

CO / H2

substrate

productreactor

HRh(CO)(L)3

decanter

P



make up purge(tars)

in aqueous layer L =SO3Na 3

•• limited by alkene solubility in water

61

+ CO / H2CHORuhrchemie/Rhône Poulenc,

two Phase Process

gas recycle & off gas

Catalyst-Recycling VII

L =

P

SO N

hydrophilic ligand: TPPTS

organic layerproduct



SO3Na 3

solubility: > 1 kg / l H2O

•• process intensification

=> reactor & decanter in one unitCO / H2

propene




•• Homogeneous Homogeneous Catalytic ProcessesCatalytic ProcessesHydrogenationHydrogenationHydroformylationHydroformylationCarbonylation of MethanolCarbonylation of Methanol ((Monsanto acetic acid & Monsanto acetic acid & acetic anhydride process)acetic anhydride process)





62

Monsanto Acetic Acid ProcessMonsanto Acetic Acid ProcessCarbonylation of MethanolCarbonylation of Methanol

[RhI2(CO)2]-

CH3OH + CO CH3COOH -

oxidativeaddition

RhCO

II

CO

CH3

Imigratoryinsertionli i ili i i

- -

-

RhCO

COI

I

I

COassociation

insertion

RhC

II

COI

CH3

O

II

C CHO

COH3C C

I

OCH3COOH

HI H2O

CH3OH CH3I

ν = 16ν = 16 ν = 16ν = 16

ν = 18ν = 18rate limitingrate limiting



•• New BP process uses [IrI2(CO)2]- with Ru2(CO)6I2(μ-I)2 as cocatalyst

•• Currently ~ 3.5 Mt/a produced worldwide, 60% of all acetyl compounds based on this process.

reductiveelimination

RhCO

I

I

C

CO

CH3 COI

ν = 18ν = 18

BP Cativa Acetic Acid ProcessBP Cativa Acetic Acid ProcessCarbonylation of Carbonylation of MethanolMethanol

O

IrCO

I

I

CO

Me

Ir

ICO

I

I

CO

MeOH

MeI

HI

H2O

MeO

MeO

I

IrCO

I

II

O

Me

OC



ratedeterminingCO

MeOH

IrCO

I

II

O

Memigratoryinsertion

Hessen/Elsevier

63

TennesseeTennessee--Eastman, Acetic AnhydrideEastman, Acetic AnhydrideCarbonylation of Methyl AcetateCarbonylation of Methyl Acetate

-

O

oxidativeaddition

RhCO

II

CO

CH3

Imigratoryinsertion

18 18rate limitingrate limiting

[RhI2(CO)2]-H3CC(O)OCH3 + CO CH3C(O)O(O)CCH3

- -

-

H3COO

reductiveli i ti

RhCO

COI

I

COassociation

RhC

II

COI

CH3

O

RhI

IC CH3

OCO

H3C CI

O

LiI

CH3I

LiOO

OO

ν = 16ν = 16 ν = 16ν = 16

ν = 18ν = 18rate limitingrate limiting



elimination RhCO

ICO

3O

ν = 18ν = 18

•• Process conditions are highly corrosive! => Expensive Hastelloy must be used.

•• Catalyst is stabilized by addition of small amounts of H2.[Rh(CO)2I2]- + 2 HI [Rh(CO)2I4]- + H2

[Rh(CO)2I4]- RhI3 (sol) + 2 CO + I-

TennesseeTennessee--Eastman, Acetic AnhydrideEastman, Acetic AnhydrideCarbonylation of Methyl AcetateCarbonylation of Methyl Acetate



Flow scheme of the processFlow scheme of the process

64









isomerization

n : i = 93 : 7

three step processthree step process

Hydrocyanation of ButadieneHydrocyanation of ButadieneDuPont ADN ProcessDuPont ADN Process

CN + HCN CNNC

Ni[P(O-tol)3]4

+ HCN70°C, low pressurehigh ligand excessHCN dosation

CNCN

+Ni[P(O-tol)3]4

3 : 2



Nylon 6,6Nylon 6,6

ADNADN[ Lewis acid ]

•• ca. 800.000 t/a ADN

HCN-sw2

65

Mechanism of the Hydrocyanation ReactionMechanism of the Hydrocyanation Reaction

L NiH

CN

LL

- LHCN

CN L

+ L

NiL

L

H

CN

CNL2Ni CN

NiL4 NiL3

- L



Nickel Nickel -- allyl allyl -- mechanism for 1,3mechanism for 1,3--dienes (L = phosphite)dienes (L = phosphite)

CN

HCN-sw16

Deactivation of the CatalystDeactivation of the Catalyst

L4Ni+ HCN

NiH

CNL

LL

- L

+ L

- L

+ LNNi

LL

H

CN

RL3Ni

- H2+ HCN

L2Ni(CN)Ni(CN)22

•• large excess of ligand necessary

•• HCN concentration has to be low

reaction rates are relatively low



•• loss of nickel by formation of Ni(CN)2

•• sophisticated engineering concerning HCN injection

•• recycling of the catalyst is expensive

HCN-sw3

66

Considerations About the MechanismConsiderations About the Mechanism

angle

The Role of the Bite AngleThe Role of the Bite Angle

P

NiP

PP

PNC

1

P

7 square planar 90°

1, 4, 6 tretragonal 109°

120°

120°

species structureangle

P - Ni - P

trigonal-bipyr.

trigonal2

3, 5

HCN

P

RNC

P

2 CN

Ni PP

P

H

CN

Ni

PP

R

P

NiPP

6

3



HCN

P

R

5

CN

NiH

PP

4

CN

NiP

P

H

R

NiP

CNP

CN7

Hydrocyanation of Styrene Applying Xantphos LigandsHydrocyanation of Styrene Applying Xantphos Ligands

30

40

50

60

105°

112°113° 114°

117°

d [%

]

0

10

20

30

P(O

-p-to

l)3

dppe

dppp

dppb

BIN

AP 1a 1b 1c 1d 1e 1f

78° 87° 98° 85°140°

yiel

d

ligand

T = 60°C; t = 18h; L/Ni = 1.2; sty./HCN/Ni = 40 / 40 / 1; a) L/Ni = 5

a)



1a - f

O

X RR

PAr2PAr2

ligand a b c d e f

X H,H SiMe2 S CMe2 CMe2 -

R H H Me H H H

Ar Ph Ph Ph Ph 3,5-(CF3)2-Ph Ph

Mirko Kranenburg, J. Chem. Commun. 1995, 2177-2178.

HCN-sw7

67

Du Pont ADN Process IDu Pont ADN Process I

CN

isom.reactor

distil.

distil.

flashdistil.reactor

flashdistil.



catalystmake-up

catalystmake-up

CNcatalystcatalyst

HCN

Du Pont ADN Process IIDu Pont ADN Process II

byproductssolvent

CN

distil.

distil.

liquid-liquid

extraction

flashdistil.reactor



catalystmake-up

HCN

NCCNcatalyst

68

Hydrocyanation of ButadieneHydrocyanation of ButadieneTriptyceneTriptycene--Based Large Bite Angle LigandsBased Large Bite Angle Ligands

Large defined bite angleLarge defined bite angleVery rigid backboneVery rigid backboneLimited flexibility rangeLimited flexibility range

PPh2Ph2PLimited flexibility rangeLimited flexibility range

Cl1a

Cl1

Pt

P1

P1a

ACH

Ni(cod)2 / LCN +

CN

3-PN 2M3BN

t [h]t [h] Conv. [%]Conv. [%] Sel.Sel.(3PN)(3PN) [%][%]


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK HCNHCN--gngn135135

XX--ray crystal structure of LPtClray crystal structure of LPtCl22PP--P distance = 3.61 P distance = 3.61 ǺǺPP--PtPt--P bite angle = 107.53P bite angle = 107.53°°

W. Ahlers, R. Paciello, D. Vogt, P. Hofmann (BASF) WO02/083695, (W. Ahlers, R. Paciello, D. Vogt, P. Hofmann (BASF) WO02/083695, (2002)2002)

33 5959 97.897.855 8787 95.395.3

Ni/BD/ACH = 1:100:200; L/Ni = 1; T = 90Ni/BD/ACH = 1:100:200; L/Ni = 1; T = 90°°C;C;0.018 mmol Ni(cod)0.018 mmol Ni(cod)22; 2ml dioxane; 2ml dioxane

L. Bini, et al., L. Bini, et al., J. Am. Chem. Soc.J. Am. Chem. Soc. 20072007, , 129129, 12622., 12622.

last change: 071114

Hydrocyanation of ButadieneHydrocyanation of ButadieneTriptyceneTriptycene--Based Large Bite Angle LigandsBased Large Bite Angle Ligands

P

PNi(cod)

P

3PN

CN

PNi0

PNi0

PP

Ni0P

PNiII

P H

CN

2M3BN HCNPPh2Ph2P



CNCN

PNiII

P

CN

CN

L. Bini, C. ML. Bini, C. Müllerüller, J. Wilting. L. Chrzanowski, A.L. Spek, D. Vogt, , J. Wilting. L. Chrzanowski, A.L. Spek, D. Vogt, J. Am. Chem. Soc.J. Am. Chem. Soc. 20072007, , 129129, 12622, 12622--12623.12623.

last change: 071114

69









Direct Oxidation of EtheneDirect Oxidation of EtheneWacker ProcessWacker Process

[Pd(0)/ Cu(II)]C2H4 + 1/2 O2 CH3CHO

•• An important feature is that the oxygen atom in the product acetaldehyde stems An important feature is that the oxygen atom in the product acetaldehyde stems

C2H4 + PdCl2 + H2O H3CCHO + Pd(0) + 2 HCl

Pd(0) + 2 [CuCl4]2- [PdCl4]2- + 2 [CuCl2]-

2 [C Cl ]- + 1/2 O + 2 HCl 2 CuCl + 2 Cl- + H O

•• The whole process only becomes catalytic by the reoxidation of PdThe whole process only becomes catalytic by the reoxidation of Pd(0)(0) with Cuwith Cu(II)(II)..

from water by nucleophilic attack of the coordinated olefin.from water by nucleophilic attack of the coordinated olefin.



2 [CuCl2]- + 1/2 O2 + 2 HCl 2 CuCl2 + 2 Cl + H2O

•• Behalf of ethene, all other olefins give the corresponding ketone in the Wacker Behalf of ethene, all other olefins give the corresponding ketone in the Wacker oxidationoxidation..

•• Substitution of water is possible (e.g. by CHSubstitution of water is possible (e.g. by CH33COOH), giving rise to other COOH), giving rise to other productsproducts..

70

Direct Oxidation of EtheneDirect Oxidation of EtheneWacker ProcessWacker Process

[Pd(0)/ Cu(II)]C2H4 + 1/2 O2 CH3CHO

[PdCl4]2-

-Pd

Cl

Cl

Cl- Cl-

2 CuCl1/2 O2

- H2O

2 HClν = 16ν = 16

H2O

Pd0

Cl

PdCl

Cl

H2O

-ClH OPd

Cl

Cl

H2O - - H+

- Cl- H2O

- Cl-- HCl- H2O

2 CuCl2

H3C CH

O

ν = 16ν = 16

ν = 16ν = 16

16 16

nucleophilic attacknucleophilic attackby Hby H22OO



PdCl

Cl

H2O

OH

OH

PdH

Cl

H2O

OH

- Cl-

+ Cl-ν = 16ν = 16

ν = 16ν = 16

ν = 16ν = 16

d[CH3CHO]

dt= k

[C2H4][PdCl42-]

[H+][Cl-]2

Wacker ProcessWacker Process[Pd(0)/ Cu(II)]

C2H4 + 1/2 O2 CH3CHO

•• One stage processOne stage process

Conversion limited to 35 Conversion limited to 35 -- 40% 40% =>=> gas recycle necessarygas recycle necessary

High purity gases are needed to avoid purges:High purity gases are needed to avoid purges:

Two process variants operated

High purity gases are needed to avoid purges:High purity gases are needed to avoid purges:pure Opure O2299.9 % ethene99.9 % ethene

TiTi--equipment needed (highly corrosive HCl in oxidative medium)equipment needed (highly corrosive HCl in oxidative medium)

But, low pressureBut, low pressure

•• Two stage processTwo stage process

Total conversion of ethene Total conversion of ethene =>=> no gas recycle no gas recycle =>=> raw gases usedraw gases used



g yg y gg

But higher pressure + two reactors But higher pressure + two reactors =>=> higher investment higher investment

TradeTrade--off betweenoff between •• low investment + costly raw materialslow investment + costly raw materials•• high investment + cheap raw materialshigh investment + cheap raw materials

(determining factor is the price of pure O(determining factor is the price of pure O22 !)!)

71









Ethene OligomerizationEthene Oligomerizationαα--OlefinsOlefins

Application Market share ( % ) α-Olefin cutUSA Western

EuropeJapan

αα--Olefin marketsOlefin markets

Europe

Detergents 32 56 35 C10-C20+

Copolymers 26 13 37 C4-C8

Plasticizer 12 8 22 C6-C10

Polyalphaolefins 9 12 * C10



Polyalphaolefins 9 12 C10

Others 21 11 6

* included in "Others"C. S. Read, R. Willhalm, Y. Yoshida in The Chemical Economics Handbook Marketing Research Report “Linear Alpha-Olefins“, SRI International 1993, 681.5030A.

72


Final Products Olefin Consumption (103 t)

USA Western Europe

Uses of higher linear Uses of higher linear αα--olefins 1992 (Stanford Research Institute)olefins 1992 (Stanford Research Institute)

USA Western Europe

Detergent Alcohols 215 150

Plasticizer Alcohols 91 34

Amines and -Derivatives 25 *

α -Olefinsulfonates (AOS) 10 3

Linear Alkylbenzenes (LAB) 11 40

Copolymers (HDPE LLDPE) 208 60



Copolymers (HDPE, LLDPE) 208 60

Synthetic Lubricants (SHC) 70 50

Lubricant Additives 25 40

Total 787 385

* unknown


Comparison of product qualities of technical CComparison of product qualities of technical C66--CC1818 αα--Olefins Olefins

Quality [wt. % α-olefin]Wax-cracking Chevron Ethyl SHOP

α-Olefins 83 - 89 91 - 97 63 - 98 96 - 98

Branched olefins 3 - 12 2 - 8 2 - 29 1 - 3

Paraffins 1 - 2 1.4 0.1 - 0.8 0.1

Dienes 3 - 6 - - -



A. M. Al-Jarallah, J. A. Anabtawi, M. A. B. Siddique, A. M. Aitani, A. W. Al-Sa´doun, Cat. Tod. 1992, 14, 1.

Monoolefins 92 - 95 99 > 99 99.9

73

Ethene OligomerizationEthene OligomerizationShell Higher Olefin Process (SHOP)Shell Higher Olefin Process (SHOP)

NiOO

PPh Ph

- 1,5-CODNi

OO

PPh Ph

H

PPh2

COOHSHOP ligand:SHOP ligand:

pn

en

CH2=CH2

CH =CH

NiO

PH

NiO

PNi

O

P

RnRn

Willi Keim



p1

p2

CH2=CH2

CH2=CH2

CH2=CH2

NiO

PNi

O

P

e2 e1

p1, p2, p3, ... propargation stepse1, e2, e3, ... elimination steps

50

60

n, %

w C6 - C10C20+

Shell Higher Olefin Process (SHOP)Shell Higher Olefin Process (SHOP)Product DistributionProduct Distribution

0

10

20

30

40

0 4 0 5 0 6 0 65 0 7 0 75 0 8 0 85 0 9

Prod

uct d

istr

ibut

ion

C12-C18

C4



0,4 0,5 0,6 0,65 0,7 0,75 0,8 0,85 0,9

Growth factor, K

Catalysis_24

•• The chain length of the α-olefins is determined by the geometric factor K of molar growth

74

Shell Higher Olefin Process (SHOP)Shell Higher Olefin Process (SHOP)

products

reactors

phaseseparation

C H

Catalyst

C2H4flash

distillation

Catalyst purge

•• The catalyst complex is soluble in butanediol 1 3



•• 98% linear α-olefins are obtained as important intermediates for low density polyolefins and detergents.

•• The catalyst complex is soluble in butanediol-1,3

•• Shell’s higher olefin process was the first example using a two-phase catalyst separation.

Shell Higher Olefin Process (SHOP)Shell Higher Olefin Process (SHOP)plant principleplant principle

What to do with (relatively low value) 1What to do with (relatively low value) 1--butene and C18butene and C18++ alkenes?alkenes?

•• Isomerize to internal alkenes (Na/K on SiOIsomerize to internal alkenes (Na/K on SiO22 cat.)cat.)

•• Olefin metathesis to intermediate chain length internal Olefin metathesis to intermediate chain length internal alkenes (Coalkenes (Co--Mo oxide catalyst) Mo oxide catalyst)



•• CoCo--catalyzed hydroformylation that converts internal catalyzed hydroformylation that converts internal alkenes to mainly terminal aldehydesalkenes to mainly terminal aldehydes

Hessen/Elsevier

75

Shell Higher Olefin Process (SHOP)Shell Higher Olefin Process (SHOP)

Ethylene

AO Product DistillationEthylene OligomerizationLight EndsColumn

Heavy EndsColumn

Reaction Separation Product Wash

Catalyst

y

C6 - C8

C8 - C10

C6

C8

C10

Isomerization / Disproportionation

Light RecycleDIST

DIS

IT

Catalyst

Bleed

P PurificationI IsomerizationD Disproportionation

c.w.



C10 - C11

C11 - C12

C13 - C14

C15 - C19

C10

C12

C14

C16

C18AO Feed

PID

Heavy Recycle

IL

T

LAT

N

IO

ILLAT

N

IO

Internal Olefins alpha - Olefins









76

Olefin Metathesis CatalysisOlefin Metathesis CatalysisM CHR

RHC CHR

M CHR

RHC CHR

M

RHC

CHR

CHR

Catalyses:Catalyses:

RHC CHR RHC CHR RHC CHR2+

cross metathesis

ring opening / ring closing metathesis



g p g g g

CH2H2C

n n H2C CH2+

Hessen/Elsevier

Olefin Metathesis PolymerizationOlefin Metathesis PolymerizationROMP-polymerisation

(ring-opening metathesis)

R

(Acyclic diene metathesis)ADMET-polymerisation

n



H2C CH2+ n

nX

X

H2CX

CH2

Hessen/Elsevier

77

WellWell--Defined Metathesis CatalystsDefined Metathesis Catalysts

RuClCl CHPh

N N

Mo CHRN

(CF ) CHO ClPCy3(CF3)2CHO

(CF3)2CHO

Mo CHRN

Cy

SchrockGrubbs

Ru catalyst highlytolerant to polar functionalities:

Richard Schrock Bob Grubbs



OO

Mo CHRy

Cy Schrock/Hoveyda

functionalities:

Highly valuablein organic synthesis

Hessen/Elsevier









78

PolyolefinsPolyolefins

By free-radical polymerization:

LDPE : Long-chain branching amorphous polyethene; films, packaging.

B t l t l d l i tiBy metal-catalyzed polymerization:

HDPE: Linear polyethene chain; high strength, stiffness;pipes, containers, caps, closures.

LLDPE: Short-chain branching; properties and use dependent on comonomer type and content.

PP: Isotactic propene homopolymer. High rigidity;ersatile properties large range of applications



versatile properties; large range of applications

Heterophasic copolymer. Elastomeric (E/P copolymer) phase dispersed in a homopolymer matrix; impact resistant.

Random copolymer. Ethylene and/or butene incorporated into PP chain; improved transparency.

Hessen/Elsevier

World Production PolyetheneWorld Production Polyethene

~ 45 Mt/a in 2000~ 45 Mt/a in 2000



79

Catalyst Families for Olefin PolymerizationCatalyst Families for Olefin Polymerization

Ziegler catalysts

transition-metal halide + Al-alkyl( ll lid t)(usually on a solid support)

Phillips catalystCr-species on SiO2 support

"Single-site" catalysts



Single-site catalysts

Well-defined organometallic complexes(can be used in solution or on a solid support)

Hessen/Elsevier

Generations of Ziegler CatalystsGenerations of Ziegler Catalysts

1st TiCl3 / AlEt2Cl

productivity(kg PP/g Ti)

% i-PP

5 90

TiCl3 / isoamylether /AlCl3 / AlEt2Cl

MgCl2 / ester / TiCl4AlEt3 / ester

MgCl2 / ester / TiCl4AlEt / 1 3 di th

15

300

600

95

92

98

2nd

3rd

4th



AlEt3 / 1,3-diether

MgCl2 support greatly improves effectivity of Ti'external donors' convert sites with poor selectivity to eitherselective or inactive sites

Hessen/Elsevier

80

CosseeCossee--Arlman MechanismArlman Mechanism(migratory insertion)

CH2R

MXX

CH2R

MXX CH2ethene

M

X

X

X

CH2RCH CH R

M

X

X

X CH2



M

X

X

X

X CH2

CH2M

X

X

X

XCH2

CH2 CH2R

Hessen/Elsevier

Alkene PolymerizationAlkene Polymerization

•• Cossee Cossee -- Arlman MechanismArlman Mechanism

Cl Cl

[TiCl3]n

AlEt3

polyethylene Cl

ClTi

Cl

Cl

ClTi

ClCl

ClTi

Cl

polyethylene



Cl

ClTi

Cl

Catalysis_27

81

Isospecific Active Sites in Ziegler-Natta Catalysis

Cl Ti

Cl*R

Cl M

L*R

TiCl3 MgCl2/TiCl4/donor

Cl Ti Cl

ClTiCl

Cl Ti Cl

ClML



L = donor or Cl

•• Site determines orientation of chain ; monomer minimizes interaction with chain

•• Stereospecificity by enantiomorphic site control

Hessen/Elsevier

Single-Site (Zirconocene) Polymerization Catalyst(Sinn, Kaminski; 1978-1980)

cocatalyst: MAO = methylalumoxane = "[(CH3)AlO]n"

MAOMAO

ethene

ZrCH3

ZrCH3

CH3Zr

Cl

Cl- CH3[MAO]



Zr CH3 ZrCH3

ZrCH3

Hessen/Elsevier

82

Alkene PolymerizationAlkene PolymerizationFliping Mechanism for MetallocenesFliping Mechanism for Metallocenes

•• catalyst activationcatalyst activation



AlO

AlO

AlO

Al+ZrClCl

Zr CH3MAO

Methylaluminoxane (MAO)Methylaluminoxane (MAO)

•• catalyst activationcatalyst activation

Selective Polymerization of PropeneSelective Polymerization of Propene

C2vTiClCl

atactic

C2ZrClCl

isotactic

HansHans--H. BrintzingerH. Brintzinger



W. Kaminsky, M. Arndt in Appl. Homog. Catal. with Organomet. Comp. (Eds.: B. Cornils, W. A. Herrmann) Vol. 1, VCH 1996, pp. 220-236.

CSHfClCl

syndiotactic

83

Propene PolymerizationPropene PolymerizationAnalysis of relative stereochemistryAnalysis of relative stereochemistry

m m m rrm m m m m

r = r = rac; rac; m =m = mesomeso

Triad = rmTriad = rmPentad = mmmmPentad = mmmm

mmmm

mmmr mmrr

mrrm

mmrmmmmr

mmmm



δ 13C

m m m mrm m m m m

δ 13C

One ‘mistake’One ‘mistake’Hessen/Elsevier

Catalytic Trimerization of Ethene

B(C6F5)3 Ti MeMe

TiMe

MeMe

ethene1-hexene

[MeB(C6F5)3]

+ Ti

1-hexene+ Ti

2 ethene

+ TiH

proposed catalyticcycle

involves Ti(IV)-Ti(II)states



+ Tiethene

H statesinduced by coordinated arene

Hessen et al. Organometallics 21 (2002) 5122Budzelaar et al. Organometallics 22 (2003) 2564

Hessen/Elsevier

84

Chromium Trimerization Catalysts

+ MAO

N NN

R'R'

R'

CrR R

R

Cr(O2CR)3

AlEt3HN

WO 00/58319 (BASF)

Koehn et al. Angew. Chem.Int. Ed. 39 (2000) 4337

1-alkene trimerisationR

ethene trimerisationPhillips petroleumvarious patents



WO 02/04119 (BP)

high activity ethene trimerisation

+ MAOCr

PN

P

O

Ar

Ar

Ar

RR R

Wass et al.Chem. Commun.(2002) 858

Hessen/Elsevier

Polymerization Catalysts Late Transition Metals

iPrNO

AriPr

iPrNN

Pd

iPr

iPriPrNi

PhMeCN

PdMe OEt2

Brookhart, Johnson Bennett, Grubbs

tolerant of functional groups, but slow + poor comonomer incorporation



iPr

iPr

NN

Fe

iPr

iPrN

Cl Cl/ MAO

Brookhart,Small, BennettGibson

highly active, but mainlyfor ethene polym./oligom.

Hessen/Elsevier

85

NNNi

Br BrNN

Ni

Br Br

NNNi

Br Br

Polyethene with Designer CalalystsPolyethene with Designer Calalysts


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK Polymers_02/169

highly branchedhighly branched=> rubber, elastic=> rubber, elastic

polymer with short branchespolymer with short branches=> soft, films=> soft, films

highly linear polymerhighly linear polymer=> hard, fibers=> hard, fibers

SupplementSupplement



86










- LLn-1M

HH

YY 18 16 18 16


++ HHYY

Ln-2MHH

YY

RHH

-- LLMMLLnn MMLLnn--11


ν = 18, 16ν = 18, 16 ν = 16, 14ν = 16, 14

ν = 18, 16ν = 18, 16

ν = 16, 14ν = 16, 14


associationassociationν = 18, 16ν = 18, 16reductive eliminationreductive elimination



+ L RLn-2M

YY

HH

RYY

HH

ν = 16, 14ν = 16, 14


ν = 18, 16ν = 18, 16

Catgen_sw1

87

Elementary Reaction StepsElementary Reaction Steps

Catalytic Cycles are Composed of sequential Catalytic Cycles are Composed of sequential elementary reaction stepselementary reaction steps

•• ligand coordination/ dissociation/ exchangeligand coordination/ dissociation/ exchange•• migratory insertion/ deinsertionmigratory insertion/ deinsertion•• nucleophilic or electrophilic attacknucleophilic or electrophilic attack•• oxidative addition/ reductive eliminationoxidative addition/ reductive elimination



•• oxidative coupling/ reductive cleavageoxidative coupling/ reductive cleavage•• cycloaddition reactions (reversible)cycloaddition reactions (reversible)

Hessen/Elsevier

Reaction Mechanisms of dReaction Mechanisms of d--Metal ComplexesMetal ComplexesLigand Substitution ReactionsLigand Substitution Reactions

•• For a consideration of the rates of reactions, the thermodynamic formation For a consideration of the rates of reactions, the thermodynamic formation constant is not a useful measure.constant is not a useful measure.

TheThe nucleophilicitynucleophilicity describes thedescribes the rate of attackrate of attack of a certain ligand (Lewisof a certain ligand (LewisThe The nucleophilicitynucleophilicity describes the describes the rate of attackrate of attack of a certain ligand (Lewis of a certain ligand (Lewis base) relative to another reference in a nucleophilic substitution reaction.base) relative to another reference in a nucleophilic substitution reaction.

Reaction rates are always relative to another rate, set as standard!Reaction rates are always relative to another rate, set as standard!

•• Substitution reactions span a wide range of ratesSubstitution reactions span a wide range of rates

-- Aqua complexes of group 1, 2, and 12 metal ions, lanthanide ions, and Aqua complexes of group 1, 2, and 12 metal ions, lanthanide ions, and some 3d metal ions exchange within nanosecondssome 3d metal ions exchange within nanoseconds



some 3d metal ions exchange within nanoseconds.some 3d metal ions exchange within nanoseconds.

-- Heavier d metals in higher oxidation states like Ir(III) or Pt(IV) can have Heavier d metals in higher oxidation states like Ir(III) or Pt(IV) can have halfhalf--lives of up to years.lives of up to years.

•• Spectator ligandsSpectator ligands are present in a complex, but not exchanged.are present in a complex, but not exchanged.They can influence the rate of an exchange reaction.They can influence the rate of an exchange reaction.

React_mech_2

88

Ligand Displacement ReactionsLigand Displacement Reactions

M L ML

XM X

X

L

associative

L

M L ML

X

M X

XSN2-like

L



- LM L M M X

dissociative+ X

L

Hessen/Elsevier

The The transtrans EffectEffect•• A strong A strong σσ--donor or donor or ππ--acceptor ligand greatly accelerates the acceptor ligand greatly accelerates the

substitution of a ligand in substitution of a ligand in transtrans positionposition

Substitutions on sqpl complexes proceed almost invariably via an Substitutions on sqpl complexes proceed almost invariably via an associative rateassociative rate--limiting stage.limiting stage.

σσ--donor donor : : OHOH-- < NH< NH33 < Cl< Cl-- < Br< Br-- < CN< CN--, CO, CH, CO, CH33-- < I< I-- < SCN< SCN-- < PR< PR33 < H< H--

ππ--acceptoracceptor : : BrBr-- < I< I-- < NCS< NCS-- < NO< NO22-- < CN< CN-- < CO, C< CO, C22HH44

transtrans--effecteffect

Effect of the trans ligand in substitutions of Effect of the trans ligand in substitutions of transtrans--[PtCl[PtClLL(PEt(PEt33))22]]


D. Vogt NIOK CAIA course 2009 Homogeneous CatalysisTUTU//ee NIOKNIOK React_mech_20

L k 1/s-1 k 2/(L m ol-1s-1)C H 3

- 1.7 10 -4 6 .7 10 -2

C 6H 5- 3.3 10 -5 1 .6 10 -2

C l- 1 .0 10 -6 4 .0 10 -4

H - 1.8 10 -2 4 .2PEt3 1.7 10 -2 3 .8

89

The The transtrans EffectEffect•• The greater the overlap of ligand orbitals with either a The greater the overlap of ligand orbitals with either a σσ-- or or ππ--Pt 5d Pt 5d

orbital, the stronger the orbital, the stronger the transtrans effect.effect.This is in line with a large ligandThis is in line with a large ligand--field splitting.field splitting.

X

CM

C

T

X•• ππ--acceptor ligands facilitate acceptor ligands facilitate nucleophilicnucleophilic attack on a dattack on a d--metal atom by removing emetal atom by removing e--

CM

C

T XC

M

C

T

Y



Y

React_mech_21

metal atom by removing emetal atom by removing edensity.density.

•• The activated complex has a tbpy structure if the The activated complex has a tbpy structure if the transtrans ligand, Y, and X have complementary ligand, Y, and X have complementary influences on the reaction rate.influences on the reaction rate.

Y

The The transtrans EffectEffectExampleExample

•• How to prepare How to prepare ciscis and and transtrans [PtCl[PtCl22(NH(NH33))22]] starting from starting from [PtCl[PtCl44]]22-- or or [Pt(NH[Pt(NH33))44]]2+2+ ??

ClCl-- has the stronger has the stronger transtrans effect effect =>=> the ammonia in the ammonia in transtrans position is substituted in the second stepposition is substituted in the second step

H3NPt

NH3

H3N NH32+ HCl

H3NPt

ClH3N NH3 HCl

H3NPt

ClCl NH3

+

-- NHNH44XX -- NHNH44XXtranstrans

PtCl Cl 2- NH3 Pt

Cl Cl - NH3 PtCl NH3



again Clagain Cl-- has the stronger has the stronger transtrans effect effect =>=> the second ammonia is introduced in the second ammonia is introduced in ciscis positionposition

ClPt

Cl ClPt

NH3 ClPt

NH3

3

-- MClMCl -- MClMClciscis

90

Steric EffectsSteric Effects

•• Hydrolysis of Hydrolysis of ciscis--[PtClL(PEt[PtClL(PEt33))22] ] at 25 at 25 °°CC

Steric crowding at the reaction center usually inhibits associative reactions Steric crowding at the reaction center usually inhibits associative reactions and facilitates dissociative reactions.and facilitates dissociative reactions.



k /sk /s--11 8x108x10--22 2x102x10--44 1x101x10--66

Migratory Insertion ReactionMigratory Insertion Reaction

Homogeneous CatalysisHomogeneous CatalysisElementary StepsElementary Steps

MeCO

COCO

Me

Mechanism supported by IR and Mechanism supported by IR and 1313C NMR studiesC NMR studies

Methyl migration by nucleophilic attack at the carbonyl CMethyl migration by nucleophilic attack at the carbonyl C--atomatom

Mn

CO

OC* CO

OC

COMn

CO

C* CO

OC

CO

O

+ CO

Acyl complexAcyl complex



ΔS‡ = = --88.2 JK 88.2 JK --11molmol--11

Migratory insertion reactions play an important role in many catalytic Migratory insertion reactions play an important role in many catalytic carbonylation reactions, alkene polymerizations and other reactions carbonylation reactions, alkene polymerizations and other reactions involving substrates with ‘double’ bondsinvolving substrates with ‘double’ bonds

91

Mechanism of COMechanism of CO--Migratory InsertionMigratory Insertion

1313C label shows: Me migrates to cisC label shows: Me migrates to cis--COCO(in fact, the reverse reaction was studied; principle of (in fact, the reverse reaction was studied; principle of ‘ i i ibilit ’ li d)‘ i i ibilit ’ li d)‘microscopic reversibility’ applied)‘microscopic reversibility’ applied)

Me

Mn

CO

OC* CO

OC

COMn

CO

C* CO

OC

COMe

O

+ CO



CO

Mn

CO

C* CO

OC

COMe

O

Hessen/Elsevier

Homogeneous CatalysisHomogeneous CatalysisElementary StepsElementary Steps

Migratory insertionMigratory insertion

H

MCH2

CH2M

CH2CH3

ββ--EliminationEliminationH H

Metal(hydride) alkene complexMetal(hydride) alkene complex Metal alkyl complexMetal alkyl complex



MCH2CH3

MCH2

CH H

M

HCH2

CH2

ββ--Hydrogen is abstracted via a cyclic 4Hydrogen is abstracted via a cyclic 4--membered transition statemembered transition state

Hessen/Elsevier

92

Homogeneous CatalysisHomogeneous CatalysisMechanismMechanism Elementary StepsElementary Steps

Migratory deMigratory de--insertioninsertion

CO CH3

Opposite of migratory insertionOpposite of migratory insertion

CO

Mn

CO

C* CO

OC

COMe

OMn

CO

C* CO

OC

COMe

O

CH3

Mn

CO

CO

OC

COOC*

- CO

ββ--EliminationElimination Needs ‘open’ coordination siteNeeds ‘open’ coordination site



ML

CH2 CH3

M

CH2

CH2

H

agostic interaction

MCH2

CH2

H

CH2

CH2M

H

Stabilization of intermediate : agostic interactionStabilization of intermediate : agostic interactionHessen/Elsevier

In fact, most ‘insertions’ involve migration of a In fact, most ‘insertions’ involve migration of a nucleophile onto an unsaturated moiety, which nucleophile onto an unsaturated moiety, which can take place in various ways:can take place in various ways:

X X

Migratory InsertionMigratory Insertion

M

X

A B

XA

M AB

X1,1 migratory insertion

B1 2 migratory insertion

X

18e 16e



MB

M A1,2 migratory insertion

X migrates with MX migrates with M--X bonding electrons (CHX bonding electrons (CH33--))

and attacks theand attacks the ππ* orbital of A=B* orbital of A=B

Hessen/Elsevier

93

Oxidative AdditionOxidative Addition

P RhOP

O + CH3-I P RhOP

OCH3

ICharacteristics:Characteristics:Oxidation number +2Oxidation number +2Coordination number +2Coordination number +2

•• Nucleophilic attack of lone pair of the metal on carbonNucleophilic attack of lone pair of the metal on carbon

Three important mechanisms for oxidative addition:Three important mechanisms for oxidative addition:



p pp p

(R3P)4Pd + ClPh

DH

PdClPR3

PR3

Ph

DH + 2 PR3

CH3X > CH3CH2X > CHR2X > CyX X = halogen

00 IIII

The other two important mechanisms:The other two important mechanisms:

Oxidative AdditionOxidative Addition

HH H

•• nonnon--polar addition:polar addition:

IrPR3

XR3POC H2

IrPR3

XR3POC

H H

Ir

X

PR3

HR3POC IIIIIIII

•• radical addition in a stepwise reaction:radical addition in a stepwise reaction:

Concerted addition; nonConcerted addition; non--polar TSpolar TS



IrPMe3

ClMe3POC R

IrPR3

R3PR

Cl

Cl

RBrIr

PR3

R3PR

Cl

ClBr

IIIIIIII

Ir(I)Ir(I) Radical; Ir(II)Radical; Ir(II) Ir(III)Ir(III)

94

OrthoOrtho--MetallationMetallation

•• Via Via oxidative addition of Coxidative addition of C--H:H:

PPhClPPh3PPh

M M –– C C 120 120 –– 240 kJ/mol240 kJ/molM M –– H H 200 200 –– 280 kJ/mol280 kJ/molC C –– HH 400 400 –– 440 kJ/mol440 kJ/mol

IrH

PPh3PPh3

PPh2PPh2Ir

Cl

3PPh3

H



Oxidative addition of COxidative addition of C––C difficult:C difficult:

M M –– C C 120 120 –– 240 kJ/mol240 kJ/mol

C C –– CC 360 360 –– 380 kJ/mol 380 kJ/mol often ‘hidden’ bondoften ‘hidden’ bond

Hessen/Elsevier

Reductive EliminationReductive Elimination

Reductive elimination is the reverse mechanism of Reductive elimination is the reverse mechanism of

•• Usually, both coordination number and oxidation state Usually, both coordination number and oxidation state decrease by two!decrease by two!


IIIIIIIIRh

ClPPh3OC

Ph3PRh

CH3

OCPh3P

PPh3

O R

Cl

+ RCOCH3



backback

•• CC--C and CC and C--H (when cis!) easily eliminateH (when cis!) easily eliminate

•• Often last step in catalytic reactionOften last step in catalytic reaction

95

•• Occurs readily for M in high oxidation stateOccurs readily for M in high oxidation state

•• Pt(IV), Pd(IV), Rh(III), Ir(III), Ni(II), Pd(II)Pt(IV), Pd(IV), Rh(III), Ir(III), Ni(II), Pd(II)

•• CC C and CC and C H (H ( hen cis!)hen cis!) easil eliminateeasil eliminate

Reductive EliminationReductive Elimination

•• CC--C and CC and C--H (H (when cis!) when cis!) easily eliminateeasily eliminate

•• Often last step in catalytic reactionOften last step in catalytic reaction

(C(C--H bond forming; hydrogenationH bond forming; hydrogenationCC––C bond forming; hydroformylation etc.)C bond forming; hydroformylation etc.)

P P



P Pd CH3H3C

P

cis

Pd CH3H3C

P-P

CH3-CH3k = 1/[P]

Hessen/Elsevier

I-

Mechanism of Reductive EliminationMechanism of Reductive Elimination

•• Usually microscopic reverse of oxidative addition Usually microscopic reverse of oxidative addition mechanismmechanism

Ph2P

PtCH3P

Ph2

CH3

CH3

I

Ph2P

PtCH3P

Ph2

CH3

CH3Ph2P

PtCH3P

Ph2

CH3

CH3

PhPh Ph

+

H3C CH3 CH3IPt(IV)Pt(IV)



Ph2P

PtCH3P

Ph2

CH3Ph2P

PtIP

Ph2

CH3Ph2P

Pt

PPh2

CH3+I-

Pt(II)Pt(II)Pt(II)Pt(II)

Hessen/Elsevier

96

Mechanism of COMechanism of CO--Migratory InsertionMigratory Insertion

(CO)4Mn

L

CO

Me

(CO)4Mn

Me

C O (CO)4Mn CO

Mek1

k-1

L; k2

slow

Rate =-d[Rgt]

dt=

k1k2[L][Rgt]k-1 + k2[L]

if k-1 ~ k2[L]

if k-1 << k2[L]k1[Rgt]-d[Rgt]=

OORgt. Int. Pdct.



-d[Rgt]dt

= if k-1 >> k2[L]k1k2[L][Rgt]k-1

dt

Hessen/Elsevier

•• MetalMetal--induced coupling with two or more ligands induced coupling with two or more ligands to form a metallacycle:to form a metallacycle:

Oxidative CouplingOxidative Coupling

Moxidative coupling

(reductive cleavage)M

M M



•• For alkynes easier than for alkenes, faster when For alkynes easier than for alkenes, faster when electronelectron--withdrawing substituents presentwithdrawing substituents present

Hessen/Elsevier

backback

97

Activation of coordinated substrate:Activation of coordinated substrate:

Nucleophilic attackNucleophilic attack

OH-

2+

+

PdOH

R H

H H

R H

H H

Pd



Electron density on alkene CElectron density on alkene C--atom lower than in free alkene;atom lower than in free alkene;

Sensitive to nucleophilic attackSensitive to nucleophilic attack

Hessen/Elsevier

σ--Bond MetathesisBond Metathesis

M CH3

H H

M CH3

H H

M CH3

H H

•• Operational for dOperational for d00 complexes, for which oxidative complexes, for which oxidative addition is NOT possibleaddition is NOT possible

M CH3

D3C H

M CH3

D3C H

M CH3

CD3 H



addition is NOT possibleaddition is NOT possible

•• May beMay be operational for higher doperational for higher dnn configurations, configurations, but not but not quite proven as yetquite proven as yet

Hessen/Elsevier

98

HeterolyticHeterolytic Cleavage of DihydrogenCleavage of Dihydrogen

NEt3(+)

When HWhen H22 is dissociated into His dissociated into H++ and metal hydrideand metal hydride

fast

3+ HNEt3

+

slow

(+)RuL

L HH

H

HRuL

L

RuL

LH

Observed ‘arrested’ intermediate:Observed ‘arrested’ intermediate:



RuPh2P

PPh2

HH

NMe2RuPh2P

PPh2

NMe2

RuPh2P

PPh2

H H NMe2+

++ H2

‘hydrogen bridge’‘hydrogen bridge’

Hessen/Elsevier

αα--Elimination ReactionsElimination Reactions

M CH2R'R

α-H elimination

- R-H

R HM CHR

R

C-H addition

R-H

α-H elimination



M NR'R-H

- R-H

C-H addition

M NHR'

R

Hessen/Elsevier

99

22ππ+2+2ππ CycloadditionsCycloadditions

M CHR

RHC CHRRHC CHR

M CHR

M CHR

RC CR

M CHR

RHC CHR

symmetry-forbiddenfor organic reactions:

allowed whentransition-metalis involved



M CHR

RHC CHRRC CR

M CRis involved

Hessen/Elsevier

Olefin MetathesisOlefin MetathesisA very powerful reaction for cleaving & (re)forming of C=C bondsA very powerful reaction for cleaving & (re)forming of C=C bonds

Nobel Prize 2005 to:Nobel Prize 2005 to: -- Yves ChauvinYves Chauvin-- Richard SchrockRichard Schrock-- Robert GrubbsRobert Grubbs

CHR

CHR

M

RHC

M CHR

RHC CHRRHC CHR

M CHR

Robert GrubbsRobert Grubbs



+ 2 RHC CHRRHC CHRRHC CHRCatalyses

Hessen/Elsevier

100

PolyolefinsPolyolefinsGlobal PP DemandGlobal PP DemandGlobal PP DemandGlobal PP Demand

kT/a

95%

100%

% OP Rate

Demand

Capacity

Utilisation50 000

55,000

Global PE DemandGlobal PE DemandGlobal PE DemandGlobal PE Demand

kT/a

95%

100%

% OP Rate

Demand

Capacity

Utilisation80,000

90,000

70%

75%

80%

85%

90%

20,000

30,000

40,000

25,000

35,000

45,000

50,000

30,000

40,000

50,000

60,000

70,000

70%

75%

80%

85%

90%



1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

50%

55%

60%

65%

0

10,000

5,000

15,000

0

10,000

20,000

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

50%

55%

60%

65%

Hessen/Elsevier

Stereocontrol in C2-Zirconocene Catalysts

Pol

Pol

- Ligand dictates conformation of polymer chain



- Monomer enantioface coordination with least steric hindrance- Two 'sites' on metal related by C2 symmetry: stereopreference is the same

isotactic polymer

Hessen/Elsevier

101

Single-Site Catalysts for Ethene/1-Alkene Copols

Me2SiN

Ti

tBu

R"Constrained geometry catalyst"

(CGC)

Many variations in this systemReview: Waymouth & McKnight Chem. Rev. 98 (1998) 2587

Stevens et al. EP 0416815 (1990; Dow Chemical)

tBu

R''n



TiNPR'

R'

R'

R

Stephan et al. Organometallics 22 (2003) 1937Nova Chemicals

Hessen/Elsevier

Monocyclopentadienyl Titanium Catalysts:Unusual Behaviour!

(s-PS)syndiotacticpolystyrene

MAOTi

Cl Cl

Tg = 100oCTm = 266oC

Ishihara et al. Macromolecules 21 (1988) 3356

Ph Ph PhPhPhPh PhPhMAOCl

th



TiH3C

CH3

CH3B(C6F5)3

ethene

toluenesolvent

ethene + 1-hexenecopolymer

Pellecchia et al. Macromolecules 32 (1999) 4419

Hessen/Elsevier

102

Syndiotactic Polymerization of Styrene

PhRRS

Ph PhPhTi

R S RRSTiCp

Ph

Ti

Ph

Cp

- Catalyst is Ti(III): [CpTiR]+



- Propagation proceeds via 2,1-insertion Catalyst is Ti(III): [CpTiR]

Cavallo et al. Macromolecules 34 (2001) 2459 + 5379

- Calculations on stereoregularity: chain-end control

Hessen/Elsevier

Propene Polymerization: RegioselectivityPropene Polymerization: Regioselectivity

TiPol Pol

Ti[1,2]fast

Ti Pol

TiPol Pol

Ti[2,1]

slow

H Pol

dormant



Ti H Ti

H2 Pol-

fast fast

Hessen/Elsevier

1

NiL

H3CNi

L

X

NiNi--CC22

H

L

Dimerization of PropeneDimerization of PropeneLigand InfluencesLigand Influences

nn--hexeneshexenes

NiL

XH

CH3

L HH3C

NiX

NiNi--CC11

H

NiL

X

H

CH3

H3C

NiL

X

NiNi--CC11

H

reductive elim.reductive elim.

+

22--methylmethyl--22--pentenepentene

isomerizationisomerization



NiX

NiNi--CC22

NiNi--CC11

NiL

X

H

X

NiNi--CC22

CH3

B. Bogdanovic, Adv. Organomet. Chem. 1979, 17, 105-140.G. Henrici-Olivé, S. Olivé, Top. Curr. Chem. 1976, 67, 107-127

last change: 071121

2,32,3--dimethyldimethyl--22--butenebutene

Mechanistic Routes to Different ProductsMechanistic Routes to Different Products

NiL

2

Ni

L

2

VCH

*

1,5-COD

+ LL

Ni

Ni[Ni] Ni Ni



G. Wilke, Angew. Chem. 1988, 100, 189.

ttt-1,5,9-CDT

2

Ni

Catgen_sw8

Homogeneous Catalysis NIOK

Documents

Transcript of Homogeneous Catalysis NIOK