Question

18.15 The Wilkinson catalyst chlorotris(triphenylphosphine)rhodium(I), CIRh(PPha), brings about the catalytic hydrogenation of an alkene in homogeneous solution: R R CIRh(PPh3)3 C=C + H - RCH CHR (18.41) HH (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 H, to the catalyst 2. ligand substitution of one PPhz by the alkene 3. 1,2-insertion of the alkene into a Rh-H bond and readdition of the previously expelled PPh, ligand 4. reductive elimination of the alkane product to regenerate the catalyst (b) According to the known stereochemistry of the 1,2-ligand insertion and reductive elimination steps, what would be the stereochemistry of the product if D, were substituted for H, in the reaction?

Please give a detailed explanation.

Answer 1

Rh(pph)c oidtot 16e speie Rh Step: Rh CPPh 148species Rh (Pph) Step:2: cl 16e SpeL 'RP + H2 Rh H oxid v addute Rht Step.3 R1-Ph cR Scanned with CS CamScanner R