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 CO2 to give the bicarbonate complex (PCP)PdO2COH. 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)PdO2CH, via a decarboxylation to give the hydride, which undergoes a fast normal insertion of CO2 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.