Synthesis and Reactivity of (PCP) Palladium Hydroxy Carbonyl and Related Complexes toward CO2 and Phenylacetylene

{2,6-Bis[(di- tert -butylphosphino)methyl]phenyl}palladium hydroxide, PCPPdOH, undergoes a fast insertion of CO 2 to give the bicarbonate complex (PCP)PdO 2 COH. It also reacts with CO to give a mononuclear hydroxy carbonyl complex, (PCP)PdCOOH. The Pd−C bond of this is unreactive toward olefins. The complex undergoes a slow conversion to the formate complex, (PCP)PdO 2 CH, via a decarboxylation to give the hydride, which undergoes a fast normal insertion of CO 2 to give the formate. The hydride, (PCP)PdH, reacts with phenyl acetylene to give the acetylide complex, (PCP)PdCCPh, in a C−H exchange reaction. This is similarly obtained from the reaction of (PCP)PdMe or (PCP)PdPh with phenyl acetylene.