Organometallic Chemistry. 1

What are organometallic compounds?What do organometallic compounds do?What organometallic chemistry will you do?

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Organometallic compounds have M-C bonds

• In reality, other M compounds without M-C bonds are considered “organometallic” if they can form M-C bonds

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Organometallic Chemistry. 1

What do organometallic compounds do?What are organometallic compounds?

What organometallic chemistry will you do?

To see more:http://www.3dchem.com/table.asp

Ru3(CO)12

Ru2(cot)(CO)6

Grubb’s catalyst,famous for olefin metathesis RuCl2Pcy3(=CHPh)

What the *@&#%&s happened here???

Organometallic Chemistry. 1

What do organometallic compounds do?What are organometallic compounds?

What organometallic chemistry will you do?

• Use some important ligands

• Do some key reaction types

• Learn some fundamental concepts

Organometallic Chemistry. Ligands

Prototypical

Carbon Monoxide, COCarbonyl ligands

Why prototypical

Metal carbonyls are frequent starting materials

Metal carbonyls are known for most transition metals

Metal carbonyls are reactive — labile — CO is easily substituted

Metal carbonyls are easily studied by IR and provide information on structure, symmetry, electron density changes at metal

CO lost as gas is swept from system, pushes reaction forward

Organometallic Chemistry. Metal Carbonyls

Metal carbonyls are known for most transition metals

To see more:http://www.3dchem.com/table.asp

Fe3(CO)12Fe2(CO)9Fe(CO)5

Mo(CO)6 Ni(CO)4 Co4(CO)12

[Rh12(m12-Sn)(CO)27]4- one-step synthesis of [Pt38(CO)44]2- dianion from [PtCl6]2- potassium salt.

Organometallic Chemistry. Metal Carbonyls

Metal carbonyls clusters are big!

COMPOSITION PER CAPSULE :Iron (as iron carbonyl USP) 100mgVitamin B9 (Folic acid BP) 1,5mgVitamin B12 (Cyanocobalamine USP) 15µgVitamin C (Ascorbic acid USP) 75mgZinc (as sulfate BP) 22,5mgExcipients for one capsule.

EXCIPIENTS WITH KNOWN EFFECT :None.

PROPERTIES :Antianemic preparation with iron and folic acid.This association with Vitamin B12 and Zinc participate in the haemoglobin synthesis process.

Ferronyl (iron carbonyl)

Also:www.ferralet.com/Patient_Information/Index.aspx

Organometallic Chemistry. Metal Carbonyls

Metal carbonyls as vitamins??!!!

Organometallic Chemistry. Metal Carbonyls

Bonding in Metal carbonyls understood with MOT

Catomic orbitals

Oatomic orbitals

COmolecular orbitals

sigma bonding =donation from HOMO on C

pi bonding =donation from M to LUMO on C

Organometallic Chemistry. Concepts.1

Predicting structure

18 electron Rule or Effective Atomic Number (EAN) Rule

“a stable organometallic compound has 18 valence electrons at the metal”

Examples

Organometallic Chemistry. Concepts.1

Predicting structure

18 electron Rule or Effective Atomic Number (EAN) Rule

“a stable organometallic compound has 18 valence electrons at the metal”

Examples

And so for Ni0??Ni(CO)4

Organometallic Chemistry. Concepts.1

18 electron Rule or Effective Atomic Number (EAN) Rule

Meet some new ligands

:PPh3

:PR3

MeCN, thf, MeOH (donor solvents)

“diphos” or “dppe” = Ph2P:(CH2)2P:Ph2

:X-, :Cl-, :Br-, :OH-, :SR-

Mo(CO)5(PPh3)

Organometallic Chemistry. Concepts.1

18 electron Rule or Effective Atomic Number (EAN) Rule

Can you think of other possible ligands for organometallics?

Organometallic Chemistry. Reactions.1

Ligand Subsitution

Metal carbonyls are frequent starting materials becausemetal carbonyls are reactive — labile — CO is easily substituted

Mo(CO)6 + energy “Mo(CO)5” + CO(g)

Mo(CO)5 + L Mo(CO)5L

Predicting reactivity: use Concept 1.

18 electron Rule or Effective Atomic Number (EAN) Rule

“a stable organometallic compound has 18 valence electrons at the metal”

Organometallic Chemistry. Reactions.1

Carbonyl Substitution can be Thermal or Photolytic

Photolysis excites one electron to an antibonding orbital, and one M-C bond is broken

Mo(CO)6 + hnenergy “Mo(CO)5” + CO(g)

monosubstituted Mo(CO)5 + L Mo(CO)5L

Mo(CO)6 + heat energy “Mo(CO)3” + 3 CO(g)

trisubstituted Mo(CO)3 + 3 L Mo(CO)3L3

Thermolosis adds enough energy to break several M-C, and causes molecule to lose as many CO’s as is favorable

Organometallic Chemistry. Reactions.2

Oxidative Addition

Recognized by two characteristics:• increase of M oxidation state, Mn+ M(n+2)+

• increase in number of coordinated atoms— coordination number, CN

Fe(CO)5 + Cl2 Fe(CO)4Cl2 + CO(g)

Fe0(CO)5 + Cl2 Fe2+(CO)4Cl2 + CO(g)

CN = 5 CN = 6

Organometallic Chemistry. Reactions.2

Oxidative Addition

Does it obey the 18 e- Rule?

Fe0(CO)5 + Cl2 Fe2+(CO)4Cl2 + CO(g)

Organometallic Chemistry. Do it!!

This week’s reactions

Reaction A: Mo0(CO)6 + diphos ? + n CO(g)

Reaction B: product of A + I2 ? + n’ CO(g)

What do these reactions make? How can we tell? Ideas?

Organometallic Chemistry. Do it!!

This week’s reactions

Reaction A: Mo0(CO)6 + diphos ? + n CO(g)

Reaction B: product of A + I2 ? + n’ CO(g)

Reaction Conditions

(1) anaerobic reaction—WHY?—How?

(2) Rxn A is heated—why?

Organometallic Chemistry. Do it!!

Prep for this week’s reactions

Reaction A: Mo0(CO)6 + diphos ? + n CO(g)

Reaction B: product of A + I2 ? + n’ CO(g)

Preparation(1) clean and dry 200 3-necked flask.

(2) clean and dry stir bar

(3) anaerobic set-up: what do you know?

(4) use heating mantle

(5) ppt with hexanes

(6) filter with Hirsch funnel (what’s that?)