A NEW TYPE OF PALLADIUM(0) COMPLEX HAVING BOTH ELECTRON-WITHDRAWING AND -DONATING SITES IN A LIGAND: 5,8-DIHYDRO- AND 5,8,9,10-TETRAHYDRO-1,4-NAPHTHOQUINONE COMPLEXES

Article abstract of DOI:10.1016/S0022-328X(00)81013-X

A new type of palladium(0) complex, (5,8-dihydro-1,4-naphthoquinone)Pd(PPh3)2 and (5,8,9,10-tetrahydro-1,4-naphthoquinone)Pd(PPh3)2, having both olefin and quinone or dihydro-quinone sites in a ligand molecules was prepared.IR and 1H NMR spectroscopic studies of these complexes suggested that it is the quinone or dihydro-quinone C=C bond which is complexed to Pd.Ligand exchange reactions showed that the stability order of the olefinic quinone complexes was as follows: (1,4-naphthoquinone)Pd(PPh3)2 > (5,8-dihydro-1,4-naphthoquinone)Pd(PPh3)2 > 5,8,9,10-tetrahydro-1,4-naphthoquinone)Pd(PPh3)2.