NEW PALLADIUM, PLATINUM AND NICKEL-COMPLEXES BASED ON RIGID PHOSPHORUS AND NITROGEN-CONTAINING LIGANDS

Three new polydentate phosphorus nitrogen ligands, ,N'-(2-diphenylphos phino)phenylformimidoyl]benzene (3), diphenylphosphino)phenyl]-1,3-ben zenedicarboxamide (6) and bis iphenylphosphino)phenyl]-2,6-pyridinedic arboxamide (7) with rigid bridging groups have been synthesised. Ligan d 7 shows an unexpected large non-bonding P-P coupling of 34 Hz, which can be attributed to the interaction of the lone pairs of the two pho sphorus atoms which are directed towards each other due to hydrogen bo nding between the two amide hydrogens and the pyridine nitrogen. Compl exation experiments with these ligands showed that 3 is a good dinucle ating ligand which resulted in the isolation of nyl)phosphinophenylfor mimidoyl]benzene}dipalladium (8). In contrast only mononuclear palladi um, platinum and nickel complexes have been obtained from ligand 7, Th e crystal and molecular structure of dichloro{bis osphino)phenyl]-2,6- pyridinedicarboxamide}platinum (9) was determined by X-ray crystallogr aphy. Complex 9 crystallises in the monoclinic space group C2/c with a =35.547(3), b=9.192(1), c=24.192(2) Angstrom, beta=102.795(7)degrees. V=7925.3(13) Angstrom(3) and Z=8; the structure was refined to R-F=0.0 31 This complex has a square planar configuration around platinum, in which the two phosphorus atoms are positioned trans to each other. For comparison, mononuclear complex dichlorobis(2-diphenylphosphinoanilin e)platinum (12) was prepared and the structure elucidated by X-ray ana lysis, Complex 12 crystallises in a triclinic space group <P(1)over ba r> with a = 10.0692(12), b = 10.839(2), c = 24.350(5) Angstrom, alpha= 88.042(15), beta = 79.091 (14), gamma=75.518(11)degrees, V=2526.4(8) A ngstrom(3) and Z=2; the structure was refined to R-F = 0.0355, Tn plat inum complex 12, a square planar geometry is found but the two phosphi nes are positioned cis to each other, whereas an unusual binding of th e chloride anions is observed. (C) 1997 Elsevier Science S.A.