Isolation and structural characterization of some stable Pd(II) carboxylate complexes supported by 1,1′-bis(diphenylphosphino) ferrocene (dppf)

Although catalytically active palladium phosphine carboxylates are generally unstable, a series of such complexes are stabilized by dppf, viz. Pd(O2CR)2(dppf) [R=CF3I, CF2CF3II and CF2CF2CF3III, CHCl2IV, o-C6H4Cl VI, CH2CO2H VII, CHCHCO2H VIII]. They have been spectroscopically characterized and their structures determined by X-ray single-crystal crystallography. Two derivatives viz. Pd(O4C2-O,O′)(dppf) IX and PdCl(O2CPh)(dppf) X are included for comparison. They are invariably mononuclear with chelating phosphine and unidentate carboxylates. The more labile (and less basic) carboxylates tend to form complexes that are more resistive to reductive decomposition. Pd(O2CPh)2(dppf) V decomposes readily to PdCl2(dppf) in the presence of chlorinated solvents.