Thermolysis of Tetranuclear Palladium Clusters: Unexpected Transfer of Oxygen from a Carboxylate Group to Carbene and Carbonyl Bridging Ligands; Carbon Dioxide Insertion into C–H Bonds

Thermolysis of the tetranuclear palladium clusters [Pd₄(μ-Q)₄(μ-O₂CR)₄] (Q = CPh₂ or CO; R = Me, CMe₃, Ph, CH₂Cl or CF₃) has been found to involve inner-sphere oxidation of carbene or carbonyl ligands during which an oxygen atom transfer occurs from the carboxylate group to the carbene or carbonyl ligand; the thermolysis of the carbonyl clusters gives rise to the products of CO₂ insertion into the C–H bond of benzene or toluene used as solvents forming benzoic acid from benzene and a mixture of phenylacetic and toluic acids from toluene.