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Organometallic Chemistry. 1 What are organometallic compounds? What do organometallic compounds do? What organometallic chemistry will you do?

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Presentation on theme: "Organometallic Chemistry. 1 What are organometallic compounds? What do organometallic compounds do? What organometallic chemistry will you do?"— Presentation transcript:

1 Organometallic Chemistry. 1 What are organometallic compounds? What do organometallic compounds do? What organometallic chemistry will you do?  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 Image credits

2 Organometallic Chemistry. 1 What do organometallic compounds do? What are organometallic compounds? What organometallic chemistry will you do? To see more: Ru 3 (CO) 12 Ru 2 (cot)(CO) 6 Grubb’s catalyst, famous for olefin metathesis RuCl 2 Pcy 3 (=CHPh) What the happened here???

3 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

4 Organometallic Chemistry. Ligands Prototypical Carbon Monoxide, CO Carbonyl 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

5 Organometallic Chemistry. Metal Carbonyls Metal carbonyls are known for most transition metals To see more: Fe 3 (CO) 12 Fe 2 (CO) 9 Fe(CO) 5 Mo(CO) 6 Ni(CO) 4 Co 4 (CO) 12

6 [Rh 12 (   -Sn)(CO) 27 ] 4- one-step synthesis of [Pt 38 (CO) 44 ] 2- dianion from [PtCl 6 ] 2- potassium salt. Organometallic Chemistry. Metal Carbonyls Metal carbonyls clusters are big!

7 COMPOSITION PER CAPSULE : Iron (as iron carbonyl USP) 100mg Vitamin B9 (Folic acid BP) 1,5mg Vitamin B12 (Cyanocobalamine USP) 15µg Vitamin C (Ascorbic acid USP) 75mg Zinc (as sulfate BP) 22,5mg Excipients 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: Organometallic Chemistry. Metal Carbonyls Metal carbonyls as vitamins??!!!

8 Organometallic Chemistry. Metal Carbonyls Bonding in Metal carbonyls understood with MOT C atomic orbitals O atomic orbitals CO molecular orbitals sigma bonding = donation from HOMO on C pi bonding = donation from M to LUMO on C

9 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

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11 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 Ni 0 ?? Ni(CO) 4

12 Organometallic Chemistry. Concepts.1 18 electron Rule or Effective Atomic Number (EAN) Rule Meet some new ligands :PPh 3 :PR 3 MeCN, thf, MeOH (donor solvents) “diphos” or “dppe” = Ph 2 P:(CH 2 ) 2 P:Ph 2 :X-, :Cl-, :Br-, :OH-, :SR- Mo(CO) 5 (PPh 3 )

13 Organometallic Chemistry. Concepts.1 18 electron Rule or Effective Atomic Number (EAN) Rule Can you think of other possible ligands for organometallics?

14 Organometallic Chemistry. Reactions.1 Ligand Subsitution Metal carbonyls are frequent starting materials because metal carbonyls are reactive — labile — CO is easily substituted Mo(CO) 6 + energy  “Mo(CO) 5 ” + CO (g) Mo(CO) 5 + L  Mo(CO) 5 L Predicting reactivity: use Concept electron Rule or Effective Atomic Number (EAN) Rule “a stable organometallic compound has 18 valence electrons at the metal”

15 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 + h energy  “Mo(CO) 5 ” + CO (g) monosubstituted Mo(CO) 5 + L  Mo(CO) 5 L Mo(CO) 6 + heat energy  “Mo(CO) 3 ” + 3 CO (g) trisubstituted Mo(CO) L  Mo(CO) 3 L 3 Thermolosis adds enough energy to break several M-C, and causes molecule to lose as many CO’s as is favorable

16 Organometallic Chemistry. Reactions.2 Oxidative Addition Recognized by two characteristics: increase of M oxidation state, M n+  M (n+2)+ increase in number of coordinated atoms— coordination number, CN Fe(CO) 5 + Cl 2  Fe(CO) 4 Cl 2 + CO (g) Fe 0 (CO) 5 + Cl 2  Fe 2+ (CO) 4 Cl 2 + CO (g) CN = 5CN = 6

17 Organometallic Chemistry. Reactions.2 Oxidative Addition Does it obey the 18 e- Rule? Fe 0 (CO) 5 + Cl 2  Fe 2+ (CO) 4 Cl 2 + CO (g)

18 Organometallic Chemistry. Do it!! This week’s reactions Reaction A: Mo 0 (CO) 6 + diphos  ? + n CO (g) Reaction B: product of A + I 2  ? + n’ CO (g) What do these reactions make? How can we tell? Ideas?

19 Organometallic Chemistry. Do it!! This week’s reactions Reaction A: Mo 0 (CO) 6 + diphos  ? + n CO (g) Reaction B: product of A + I 2  ? + n’ CO (g) Reaction Conditions (1) anaerobic reaction—WHY?—How? (2) Rxn A is heated—why?

20 Organometallic Chemistry. Do it!! Prep for this week’s reactions Reaction A: Mo 0 (CO) 6 + diphos  ? + n CO (g) Reaction B: product of A + I 2  ? + n’ CO (g) Preparation (1) clean and dry 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?)

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