Chapter 9 Inorg

Chapter 9 Coordination Chemistry I: Structures and Isomers 123

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CHAPTER 9: COORDINATION CHEMISTRY I: STRUCTURES AND ISOMERS 9.1 Hexagonal: C2v C2v D2h

Hexagonal pyramidal: Cs Cs C2v

Trigonal prismatic: Cs C2v C2

Trigonal antiprismatic: Cs C2 C2h

The structures with C2 symmetry would be optically active.

9.2 a. dicyanotetrakis(methylisocyano)iron(II) or dicyanotetrakis(methylisocyano)iron(0) b. rubidium tetrafluoroargentate(III) or rubidium tetrafluoroargentate(1–) c. cis- and trans-carbonylchlorobis(triphenylphosphine)iridium(I) or cis- and trans- carbon ylchlorobis(triphenylphospine)iridium(0) d. pentaammineazidocobalt(III) sulfate or pentaammineazidocobalt(2+) sulfate e. diamminesilver(I) tetrafluoroborate(III) or diamminesilver(1+) tetrafluoroborate(1–) (The BF4

– ion is commonly called “tetrafluoroborate.”) 9.3 a. tris(oxalato)vanadate(III) or tris(oxalato)vanadate(3–) b. sodium tetrachloroaluminate(III) or sodium tetrachloroaluminate(1–) c. carbonatobis(ethylenediamine)cobalt(III) chloride or carbonatobis(ethy lenediamine)cobalt(1+) chloride d. tris(2,2-bipyridine)nickel(II) nitrate or tris(2,2-bipyridine)nickel(2+) nitrate (The

IUPAC name of the bidentate ligand, 2,2-bipyridyl may also be used; this ligand is most familiarly called “bipy.”)

e. hexacarbonylmolybdenum(0) (also commonly called “molybdenum hexacarbonyl”).

The (0) is often omitted.

9.4 a. tetraamminecopper(II) or tetraamminecopper(2+) b. tetrachloroplatinate(II) or tetrachloroplatinate(2–) c. tris(dimethyldithiocarbamato)iron(III) or tris(dimethyldithiocarbamato)iron(0) d. hexacyanomanganate(II) or hexacyanomanganate(4–)

e. nonahydridorhenate(VII) or nonahydridorhenate(2–) (This ion is commonly called “enneahydridorhenate.”)

124 Chapter 9 Coordination Chemistry I: Structures and Isomers


9.5 a. triamminetrichloroplatinum(IV) or triamminetrichloroplatinum(1+) b. diamminediaquadichlorocobalt(III) or diamminediaquadichlorocobalt(1+) c. diamminediaquabromochlorocobalt(III) or diamminediaquabromochlorocobalt(1+) d. triaquabromochloroiodochromium(III) or triaquabromochloroiodochromium(0) e. dichlorobis(ethylenediamine)platinum(IV) or dichlorobis(ethylenediamine)platinum(2+) or dichlorobis(1,2-ethanediamine)platinum(IV) or dichlorobis(1,2-

ethanediamine)platinum(2+) f. diamminedichloro(o-phenanthroline)chromium(III) or diamminedichloro(o- phenanthroline)chro mium(1+) or diamminedichloro(1,10-phenanthroline)chromium(III) or diamminedichloro(1,10-phenanthroline)chromium(1+)

g. bis(2,2-bipyridine)bromochloroplatinum(IV) or bis(2,2-bypyridine)bromochloroplatinum(2+)

or bis(2,2-bipyridyl)bromochloroplatinum(IV) or bis(2,2- bipyridyl)bromochloroplatinum(2+)

h. dibromo[o-phenylene(dimethylarsine)(dimethylphosphine)]rhenium(II) or dibrom o[o-phenylene(dimethylarsine)(dimethylphosphine)]rhenium(0) or dibrom o[1,2-phenylene(dimethylarsine)(dimethylphosphine)]rhenium(II) or dibrom o[1,2-phenylene(dimethylarsine)(dimethylphosphine)]rhenium(0) i. dibromochlorodiethylenetriaminerhenium(III) or dibrom ochlorodiethylenetriaminerhenium(0) or dibromochloro(2,2- diam inodiethylamine)rhenium(III) or dibromochloro(2,2- diam inodiethylamine)rhenium(0)

9.6 a. dicarbonylbis(dimethyldithiocarbamato)ruthenium(III) or

dicarbonylbis(dimethyldithiocarbamato)ruthenium(1+) b. trisoxalatocobaltate(III) or trisoxalatocobaltate(3–) c. tris(ethylenediamine)ruthenium(II) or tris(ethylenediamine)ruthenium(2+) d. bis(2,2-bipyridine)dichloronickel(II) or bis(2,2-bipyridine)dichloronickel(2+) 9.7 a. Bis(en)Co(III)-µ-amido-µ-hydroxobis(en)Co(III)

CoN O

N N

N

N

CoN

N

N

N

H

H2

4+



b. Diaquadiiododinitritopalladium(IV)

PdH2O ONO

ONO OH2

I

I

PdH2O ONO

ONO I

H2O

I

PdONO OH2

ONO OH2

I

I

PdH2O I

ONO OH2

I

ONO

PdONO ONO

H2O I

I

H2O

PdONOONO

OH2I

I

OH2

enantiomers c. Fe(dtc)3

FeS S

S S

S

S

FeSS

SS

S

S

S

SC

S

S

N

CH3

H

–

=

At low temperature, restricted rotation about the C—N bond can lead to additional isomers as a consequence of the different substituents on the nitrogen. These isomers can be observed by NMR.



9.8 a. triammineaquadichlorocobalt(III) chloride Isomers are of the cation:

CoH3N NH3

H3N Cl

H2O

Cl

CoH3N NH3

H3N OH2

Cl

Cl

+ +

CoCl NH3

H2O NH3

NH3

Cl

+

cis trans

mer fac

b. -oxo-bis(pentammine-chromium(III)) ion

CrO

H3N

H3N

H3N

H3N

NH3

CrO

NH3

H3N

NH3

NH3

NH3

4+

c. potassium diaquabis(oxalato)manganate(III) Isomers are of the anion:

MnH2O O

O O

O

H2O

MnOH2O

OO

O

OH2

MnO O

O O

H2O

H2O

cis enantiomers trans

– – –

9.9 a. cis-diamminebromochloroplatinum(II)

b. diaquadiiododinitritopalladium(IV) c. tri--carbonylbis(tricarbonyliron(0))

Pt

Cl NH3

Br NH3

PtONO OH2

H2O ONO

I

I

Fe Fe

C

C C

O

OOC C

C CC CO O

O

O O

O



9.10 9.11 M(AB)3

MB B

A A

B

A

MBB

AA

B

A

MA B

B A

A

B

MAB

BA

A

B

fac mer

9.12 a. [Pt(NH3)3Cl3]+

PtCl NH3

Cl NH3

NH3

Cl

PtNH3Cl

NH3H3N

Cl

Cl

+ +

fac mer

b. [Co(NH3)2(H2O)2Cl2]+

CoCl OH2

H2O NH3

NH3

Cl

CoNH3H2O

NH3H2O

Cl

Cl

+ +

CoCl OH2

Cl OH2

NH3

NH3

CoClH2O

OH2Cl

NH3

NH3

+ +

CoCl NH3

H2O NH3

OH2

Cl

CoClH3N

OH2H3N

H2O

Cl

+ +

enantiomers

H2N

CH2 C

O

O – = N O

MO O

N N

O

N

MOO

NN

O

N

MN O

O N

N

O

MNO

ON

N

O

fac mer



c. [Co(NH3)2(H2O)2BrCl]+

d. Cr(H2O)3BrClI

CrCl I

H2O OH2

OH2

Br

CrClI

OH2H2O

H2O

Br

enantiomers

CrH2O Br

I OH2

OH2

Cl

CrH2O Br

Cl OH2

OH2

I

CrH2O I

Cl OH2

OH2

Br e. [Pt(en)2Cl2]2+

PtCl N

N N

N

Cl

PtClN

NN

N

Cl

PtN N

N N

Cl

Cl

cis enantiomers trans

2+2+2+

CoH3N Cl

H3N Br

OH2

OH2

CoNH3H2O

NH3H2O

Cl

Br

+ +

CoCl OH2

Br OH2

NH3

NH3

CoBrH2O

OH2Cl

NH3

NH3

+ +

CoBr NH3

H2O NH3

OH2

Cl

CoBrH3N

OH2H3N

H2O

Cl

+ +

enantiomers

CoCl NH3

H2O NH3

OH2

Br

CoClH3N

OH2H3N

H2O

Br

+ +

enantiomers



f. [Cr(o-phen)(NH3)2Cl2]+

+ +

CrCl NH3

NH3

Clenantiomers

N

NCr

ClH3N

H3N

Cl

N

N

+

CrCl NH3

Cl

NH3

N

N

+

CrH3N Cl

NH3

Cl

N

N

trans Cl ligands trans NH3 ligands g. [Pt(bipy)2BrCl]2+

2+

PtCl

Br

enantiomers

N

N

N

NPt

Cl

Br

N

N

N

N

2+

2+

Pt

Br

N

N

Cl

N

N

h. Re(arphos)2Br2 Abbreviating the bidentate ligands As P:

ReBr AsBr As

P

P

ReBrAsBrAs

P

P

ReBr PBr P

As

As

ReBrPBrP

As

As

ReBr As

Br P

As

P

ReBrAs

BrP

As

P

ReAs As

P P

Br

Br

ReAs P

P As

Br

Br



i. Re(dien)Br2Cl

ReN Br

N Br

Cl

N

ReNBr

NBr

Cl

N

ReN Br

N Cl

Br

N

ReN N

N Cl

Br

Br

ReN N

N Br

Cl

Br 9.13 a. M(ABA)(CDC)

MD A

C B

A

C

MB AA D

C

C

MD AC A

B

C

MDACA

B

C

b. M(ABA)(CDE)

MD A

C B

A

E

MDA

CB

A

E

MB A

A D

C

E

MD A

C A

B

E

MDA

CA

B

E

MD B

C A

A

E

MDBCA

A

E



9.14

MB CA B

A

C

MBCAB

A

C

MB C

A B

A

C

MB BA A

C

C

MBBAA

C

C

MB AA C

B

C

MBBAC

B

C

MBC

AB

A

C

MB C

C B

A

A

MB C

A A

B

C

MBC

AA

B

C

9.15 a. The “softer” phosphorus atom bonds preferentially to the soft metal Pd (see Section 6.6.1).

b, c. Abbreviating the bidentate ligands N P:

NiCl N

Cl N

P

P

NiClN

ClN

P

P

NiCl P

Cl P

N

N

NiClP

ClP

N

N

NiCl NCl P

N

P

NiClN

ClP

N

P

NiN N

P P

Cl

Cl

NiN P

P N

Cl

Cl



9.16 a, b. Abbreviating the bidentate ligands N P and O S:

MCl O

Cl P

N

S

MClO

ClP

N

S

MCl S

Cl P

N

O

MClS

ClP

N

O

MCl O

Cl N

P

S

MClO

ClN

P

S

MCl S

Cl N

P

O

MClS

ClN

P

O

MO NS P

Cl

Cl

MO P

S N

Cl

Cl

9.17 The single C–N stretching frequency indicates a trans

structure for the cyanides (the symmetric stretch of the C—N bonds is not IR active), while the two C–O bonds indicate a cis structure for the carbonyls (both the symmetric and antisymmetric C–O stretches are IR active). As a result, the bromo ligands are also cis.

CoBrBr

CC

C

C

O

N

O

N

–



9.18 There are 18 isomers overall, six with the chelating ligand in a mer geometry and 12 with the chelating ligand in a fac geometry. All are enantiomers. They are all shown below, with dashed lines separating the enantiomers.

9.19 a. b. c. d.

9.20 All are chiral if the ring in b does not switch conformations. 9.21 20b 20c top ring: , bottom ring:

9.22 a, b. 1. O

Mo S

MoMo

O W

OS

Mo O

MoMo

O W

O

Cs C3v

2. O

Mo S

MoMo

S W

OS

Mo O

MoMo

O W

S

Cs Cs

3. S

Cr O

MoMo

Se W

OO

Cr O

MoMo

Se W

SS

CrO

MoMo

SeW

OO

CrO

MoMo

SeW

S

C1 C1 C1 C1

Se

Cr O

MoMo

S W

OO

Cr O

MoMo

S W

SeSe

CrO

MoMo

SW

OO

CrO

MoMo

SW

Se

C1 C1 C1 C1

MOH2As

BrP

N

NH3

MBrAs

OH2P

N

NH3

MOH2As

NP

NH3

Br

MNH3As

BrP

N

OH2

MBrAs

NH3P

N

OH2

MNH3As

NP

OH2

Br

MOH2As

NH3P

N

Br

MNH3As

OH2P

N

Br

MBrAs

NP

OH2

NH3

MH2O As

Br P

N

NH3

MBr As

H2O P

N

NH3

MH2O As

N P

NH3

Br

MH3N As

Br P

N

OH2

MBr As

H3N P

N

OH2

MH3N As

N P

OH2

Br

MH2O As

H3N P

N

Br

MH3N As

H2O P

N

Br

MBr As

N P

OH2

NH3



S

Cr O

MoMo

O W

SeS

W O

MoMo

O Cr

Se

Cs Cs

c. Yes, provided the structure has no symmetry or only Cn axes. Examples are the structures with C1 symmetry in part a.

9.23 The 19F doublet is from the two axial fluorines (split by the equatorial fluorine). The 19F triplet is from the equatorial fluorine (split by the two axial fluorines). The two doubly bonded oxygens are equatorial, as expected from VSEPR considerations. Point group: C2v 9.24 Examples include both cations and anions: [Cu(CN)2]–, [Cu2(CN)3]–, [Cu3(CN)4]–, [Cu4(CN)5]–, [Cu5(CN)6]–

[Cu2(CN)]+, [Cu3(CN)2]+, [Cu4(CN)3]+, [Cu5(CN)4]+, [Cu6(CN)5]+ Based primarily on calculations (rather than experimental data), Dance et al. proposed linear structures such as the following: [Cu(CN)2]–: NC—Cu—CN

[Cu2(CN)3]–: NC—Cu—CN—Cu—CN

[Cu3(CN)4]–: NC—Cu—CN—Cu—CN—Cu—CN

[Cu2(CN)]+: Cu—CN—Cu

[Cu3(CN)2]+: Cu—CN—Cu—CN—Cu

[Cu4(CN)3]+: Cu—CN—Cu—NC—Cu—CN—Cu

Where 2-coordinate copper appears in these ions, the geometry around the Cu is linear, as expected from VSEPR. 9.25 The bulky mesityl groups cause sufficient crowding that the phosphine ligands can show

chirality (C3 symmetry) and can be considered as similar to left-handed (PL) and right-handed (PR) propellers. If two P(mesityl)3 phosphines are attached in a linear arrangement to a gold atom, three isomers are possible:

PL—Au—PL PR—Au—PR PL—Au—PR

(PR—Au—PL is equivalent to PL—Au—PR, as can best be seen with models.) NMR data at low temperature support the presence of these isomers, which interconvert at higher temperatures.

H3C

H3C

CH3

mesityl

Os

F

F

F

OO

+



9.26 The point group is D3h. A representation based on the nine 1s orbitals of the hydride ligands is:

D3h E 2C3 3C2 h 2S3 3v 9 0 1 3 0 3

A1 1 1 1 1 1 0 z2

E 2 –1 0 2 –1 0 (x, y), (x2–y2, xy) A2 1 1 –1 –1 –1 1 z E 2 –1 0 –2 1 0 (xz, yz)

The representation reduces to 2 A1 + 2 E + A2 + ECollectively these representations match all the functions for s (totally symmetric, matching A1), p, and d orbitals of Re, so all the s, p, and d orbitals of the metal have suitable symmetry for interaction. (The strength of these interactions will also depend on the match in energies between the rhenium orbitals and the 1s orbital of hydrogen.)

9.27

9.28

Re

= H

CrO OOO

N N

OO O

OMnMn

CrO OOO

N N

OO O

O

CrO OOO

N N

OO O

OMnMn

CrO OOO

N N

OO O

O

CrO OOO

N N

OO O

OMnMn

CrO OOO

N N

OO O

O

Co

O O

OO

N

N

NN

N

N

N N

N

N

N

N

N

N

N

N

N

N

N

N

N

NN

N

N

N

Co

OO

OO

N

N

Co OO

OO

N

N

Co

OO

O O

N

N

Co

OO

OO

N

N

CoOO

OO

N

N



9.29 a. Cu(acacCN)2: D2h tpt: C2v b. C6

9.30 All four metal-organic frameworks studied (MOF-177, Co(BDP), Cu-BTTri, Mg2(dobdc) ) are significantly more effective at adsorbing carbon dioxide relative to adsorbing hydrogen. This is attributed, in part, to the higher polarizability of CO2 relative to that of H2. The formation of an induced dipole in these gases by exposed cations within MOFs is an important prerequisite for adsorption. The two MOF properties that most strongly correlate with CO2 adsorption capacity are MOF surface area and MOF accessible pore volume. As these values (tabulated below) increase, the CO2 adsorption capacity increases.

MOF Surface Area ( m2 g ) Accessible Pore Volume ( cm3 g )

MOF-177 4690 1.59

Co(BDP) 2030 0.93

Cu-BTTri 1750 0.713

Mg2(dobdc) 1800 0.573 The graphs in Figure 1 of the reference clearly indicate that Mg2(dobdc) adsorbs the most CO2

at 5 bar. The arrangement and concentration of open Mg2+ cation sites on the Mg2(dobdc) surface is hypothesized to render this MOF more susceptible to CO2 adsorption. This MOF, along with Cu-BTTri, which also features exposed metal sites, are identified as the best prospects for CO2 H2 separation.

9.31 The synthesis and application of amine-functionalized MOFs for CO2 adsorption is the general topic of the reference. While the M2(dobdc) series of MOFs were proposed as excellent candidates for this functionalization (on the basis of their relatively large concentration of exposed metal cation sites), their amine-functionalization proved difficult. This was attributed to the relatively narrow MOF channels that may hinder amine diffusion into M2(dobdc) . One hypothesized solution was to prepare a MOF with the M2(dobdc) structure-type, but with larger pores. The wider linker dobpdc (below, along with dobdc for comparison) was used in the hope of obtaining MOFs with larger pores.

O

O

O

O

O

O

O

O

O

O

O

O

dobpdc

dobdc



Amine-functionalized Mg2(dobpdc)was prepared by mixing H4(dobpdc), magnesium bromide, and a small solvent volume (a mixture of N,N’-diethylformamide and ethanol) in a Pyrex container. The mixture was heated in a microwave reactor, and the M2(dobpdc) collected by filtration after cooling. Dried samples of Mg2(dobpdc)were then heated for roughly one hour at 420 °C under dynamic vacuum. After this “activation” step, Mg2(dobpdc)was stirred with an excess of N,N’-dimethylethylenediamine (mmen) in hexanes for one day. Subsequent heating under vacuum resulted in removal of residual solvents to afford mmen-functionalized Mg2(dobpdc) . The “activation” step was found necessary to completely remove residual N,N’-

diethylformamide from the Mg2+ coordination sites. 9.32 This reference discusses application of porphyrin-containing MOFs where the porphyrin provides

a binding site for Fe(III) and Cu(II). The precursor to the porphyrin linker (TCPP) is provided below; the resulting carboxylates of this linker permit its incorporation into the MOF.

HN

N

NH

N

COOHHOOC

HOOC COOH

The metallation options include premetallation and postmetallation. In premetallation, H4-TCPP-Cu and H4-TCPP-FeCl , respectively, are used as reactants for the MOF synthesis. In this case, the porphyrin linker and its bound metal ion are installed simultaneously into the MOF. This general approach afforded MOF-525-Cu, MOF-545-Fe, and MOF-545-Cu. MOF-525-Fe could not be obtained via this strategy. For this MOF, postmetallation was employed, via the reaction of MOF-525 with Fe(III) chloride; Fe(III) ions were introduced into the MOF-525 porphyrin linkers via this method.

In terms of similarities and differences, MOF-545 can be metallated with both Fe(III) and Cu(II)

via a premetallation strategy, while MOF-525 requires alternate procedures for incorporation of Cu(II) (premetallation) and Fe(III) (postmetallation), respectively.

Chapter 9 Inorg

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