CHEM 495 TRANSITION METAL CHEMISTRY – FALL 2001
Due Dec 24th, 2001

No pencil or red pen

Answer all questions

Hint – have a look at the previous answer keys for the style of answer expected

Some of the answers are not in your class notes and will require library work or other literature.

 

1. Transition metal carbenes and transition metal alkylidenes may be differentiated by the ¹³C NMR shift of the a-carbon. What are the distinctive chemical shift ranges? What does the chemical shift indicate about their relative Lewis acidity? (10 points).

2. Trans-PtCl(CH₂Ph)(PPh₃)₂ (A) undergoes a slow intra-molecular reaction (rearrangement) to form compound B with no volatile products formed. If compound A is reacted with D₂ the eventual products are Pt⁰ and C₆H₄DMe. If A is reacted with D₂ prior to the formation of B C₆H₅CH₂D is the product. What is compound Band what are the reaction steps by which it is formed? If A and B are in equilibrium, suggest the factors that determine the position of the equilibrium. Would the equilibrium constant for A -> B be larger or smaller if A was the cis isomer? (10 points)

3. What are the potential products for the migratory insertion of SO₂ into a M-R bond (R = alkyl)? (8 points).

4. The ruthenium methoxide complex, L_nRu(OCH₃) undergoes a decomposition to form a stable Ru carbonyl complex. Explain the reaction steps assuming that L is a passive, unreactive, but labile ligand. (10 points).

5. RC(O)Cl reacts with RhCl(PPh₃)₃ to yield RCl and a rhodium complex whose IR spectrum shows a strong absorption between 1850 – 2000 cm^-1. Explain this reaction in full. (10 points).