Density Functional Theory Study on Carbonyl Insertion into RhI-C Bond in Heterobimetallic Rh-M (M=Cr, Mo, W) Species

The influence of ligand and cooperative metal on carbonyl insertion in heterobimetallic Rh-M species was investigated at the B3LYP level of density functional theory. The computational results indicate that all of the transition states of the carbonyl insertion occur lately on the potential energy surface. The carbonyl insertion into the Rh-C-vinyl, bond is easier than that into the Rh-C-ethyl bond. The CO ligand promotes the carbonyl insertion into the Rh-C-ethyl bond thermodynamically, while it inhibits this reaction kinetically. The CO ligand is in favor of the carbonyl insertion into the Rh-C-vinyl bond both thermodynamically and kinetically. The reactivity of the various cooperative metals with the same ligand for the carbonyl insertion into the Rh-C-ethyl and Rh-C-vinyl bonds has following order: Cr < Mo < W. The energy decomposition analysis indicates that the lower activation energy of the carbonyl insertion into the Rh-C-vinyl bond than that of the carbonyl insertion into the Rh-C-ethyl bond should be caused by the stronger interaction energy between carbonyl and vinyl fragments in transition states of the carbonyl insertion into the Rh-C-vinyl bond than that of the carbonyl insertion into the Rh-C-ethyl bond.