The Wilkinson catalyst chlorotris (triphenylphosphine) rhodium(I), ClRh(PPh0)3, brings about the catalytic hydrogenation of an alkene in homogeneous solution:

(a) Using the following mechanistic steps as your guide, draw structures of the transition- metal complexes involved in each step. Give the electron count and the metal oxidation state at each step.
1. Oxidative addition of H2 to the catalyst
2. Ligand substitution of one PPh3 by the alkene
3. 1, 2-insertion of the alkene into a Rh-H bond and readdition of the previously expelled PPh3 ligand
4. Reductive elimination of the alkane product to regenerate the catalyst

Transcribed Image Text:

R R C=C + H2 CIRH(PPhy)s RCH;CH,R H H