PREPARATION AND ELECTROCHEMICAL PROPERTIES OF PALLADIUM(0) COMPLEXES COORDINATED BY QUINONES AND 1,5-CYCLOOCTADIENE

Article abstract of DOI:10.1016/0022-328X(83)80202-2

The complexes Pd(quinone)(COD) (COD=1,5-cyclooctadiene) are prepared by a ligand substitution reaction of Pd2(DBA)3 (DBA=dibenzylideneacetone) in the presence of both quinone and COD.Palladium(0) complexes coordinated by quinones only are formed in the reaction in the absence of COD.The cyclic voltammetric behavior of Pd(quinone)(COD) has been studied.The reduction potentials for quinones shifted toward negative values on coordination to palladium(0).The oxidation potentials for the central palladium(0) in Pd(quinone)(COD) depend on the electron-withdrawing ability of the free quinones, and are in the following series: quinone = p-benzoquinone < 5,8-dihydro-1,4-naphthoquinone ca. 1,4-naphthoquinone < duroquinone.The shift of oxidation potentials for Pd(quinone)(COD) on changing the quinones as ligands is in contrast to that of Pd(quinone)(triphenylphosphine)2.