DIPALLADIUM COMPLEXES WITH A BRIDGING ARYLENE OR DIARYLENE LIGAND - SYNTHESIS AND CNR' AND CO INSERTION INTO THE PD-C BONDS

The complexes trans-[PdEt2L2] (L = PMe3 or PEt3) reacted with 4,4'-dib romobiphenyl, 4,4'-diiodobiphenyl, 1,4-diiodobenzene, di(4-bromophenyl ) ether, di(4-chlorophenyl) sulfone, 9,10-dibromoanthracene and 4,4'-d ibromooctafluorobiphenyl to give various bimetallic palladium(II) comp lexes with a bridging arylene or diarylene ligand, trans,trans-[L2XPdR PdXL2] (L = PMe3 or PEt3; R = C6H4C6H4, C6H4, C6H4OC6H4, C6H4SO2C6H4, C14H8 or C6F4C6F4; X = Br, Cl or I). The structure of trans, trans-[(E t3P)(2)BrPdC6H4C6H4PdBr-(PEt3)(2)] has been determined by X-ray crysta llography. The complex trans, trans-[(Me3P)(2)BrPdC6H4C6H4PdBr-(PMe3)( 2)] reacts with tert-butyl, cyclohexyl and phenyl isocyanides to give the iminoacylpalladium complexes trans, [(Me3P)(2)BrPdC(=NR')C6H4C6H4C (=NR')PdBr(PMe3)(2)] (R' = Bu-t, C6H4 or Ph) through insertion of the isocyanide into the two aryl-palladium bonds. Reactions of tr ans, tra ns-[L2IPdRPdIL2] (R = C6H4C6H4, L = PEt3; R = C6H4, L = PMe3 or PEt3) with CO (1 atm) proceeded smoothly to give trans,trans-[(Et3P)(2)IPdCO C6H4-C6H4PdI (PEt3)(2)] and trans, trans-[L2IPdCOC6H4PdIL2] (L = PMe3 or PEt3), respectively, through insertion of CO into one of the aryl-p alladium bonds.