Development and mechanistic study of a new aldehyde decarbonylation catalyst

Article abstract of DOI:10.1021/ja00033a028

Rh₂(PMe₃)₂(CO)₂Cl₂ (2) has been found to catalyze the decarbonylation of aldehydes to give the corresponding alkanes. Reaction rates are comparable to those of the most active nonradical systems previously reported. A mechanistic study indicates that the turnover-limiting reaction step includes addition of the aldehydic C-H bond to an intact molecule of 2; ligand dissociation or cleavage of the chloride bridge does not occur prior to the C-H addition step. This conclusion is based on kinetic studies (d[R′H]/dt = k_obs[2[R′CHO]; R′ = n-C₁₁H₂₃; k_obs = 2.2 × 10^-4 M^-1 s^-1; ΔS^? = -26 eu) and the observation of a significant kinetic isotope effect (k_RCHO/RCDO > 1.8).