PALLADIUM(II) 2-DIPHENYLPHOSPHINOHYDROQUINONE (H(2)PPHQ) COMPLEXES - PREPARATION AND STRUCTURES OF A NOVEL CLUSTER, [(PDBR(HPPHQ))(4)]CENTER-DOT-2H2O, AND A PHOSPHINE-PHOSPHINITE COMPLEX, 2(C6H3(OH)-1,PPH(2)-3,PPH(2)O-4)]CENTER-DOT-2H(2)O

The complexes [PdCl2(PPh(3))L(2)] (L(2) = 1,4-dimethoxy-2-diphenylphos phinobenzene) [PdCl(bipy)L(2)](+) (bipy = 2,2'-bipyridine) and [PdCl2( mpy)L(2)] (mpy = 4-methylpyridine) have been prepared and their reacti ons with BBr3 studied. The first two complexes afforded products resul ting from protolytic cleavage of the phosphinohydroquinone ligand wher eas reactions of the last with BBr3 produced [PdBr(mpy)(Hpphq-O,P)] (H (2)pphq = H(2)L(1) = 2-diphenylphosphinohydroquinone) when quenched wi th methanolic sodium carbonate or, when quenched with methanol alone, a mixture which contains the novel tetrameric cluster [{PdBr(HL(1))}(4 )] and slowly deposits an unexpected phosphine-phosphinite complex, ci s-[PdBr2{C6H3(OH)-1,PPh(2)-3,PPh(2)O-4}]. H2O, on standing. The crysta l structures of the last two complexes have been determined. The palla dium tetramer was also formed when [PdBr(mpy)(HL(1)-O,P)] was treated with hydrobromic acid. The NMR spectra suggest that in solution the te tramer is in equilibrium with monomeric solvato complexes, [PdBr(solv) (HL(1)-O,P)] (solv = solvent).