MAGNETIC-PROPERTIES OF SOME NICKEL(II)-SUBSTITUTED PROPANOATE DIMERS AND THE CRYSTAL-STRUCTURE OF TETRAKIS(MU-2-METHYL-2-PHENYLPROPIONATO-O,O')BIS(TRIPHENYLPHOSPHINE)DINICKEL(II), [NI(ME2PHCCOO)2PPH3]2

The dimeric Ni(II) complexes [Ni(RCOO)2L]2 (1, R = Me2PhC, L = PPh3; 2, R = Me2PhC, L = quinoline and 3, R = Me3C, L = 2-picoline) have been synthesized. They all display a dimer type of antiferromagnetism found in similar Cu(II) and Ni(II)complexes. The crystal structure of 1 has been determined from X-ray diffraction data at 295 K. The green crystals are triclinic with a = 12.001(5), b = 14.688(5), c = 19.666(6) angstrom, alpha = 86.13(2), beta = 82.57(3), gamma = 76.718(3), Z = 2, space group P1BAR. Full-matrix least-squares refinement based on 5589 observed reflections gave a final R = 0.085. There are two crystallographically independent half molecules in the asymmetric unit. The compound has the classical dimeric structure well known for numerous Cu(II) carboxylates. Thus Ni(II) has a square-pyramidal five-coordination with P apical and Ni on average 0.276 angstrom above the basal oxygen plane. The Ni...Ni separations in the dimers average 2.759 angstrom.