SYNTHESIS, CRYSTAL-STRUCTURE AND EQUILIBRIUM STUDIES ON BIDENTATE AMINE ADDUCTS OF BIS(S-BENZYL)-BETA-N-(4-DIMETHYLAMINOBENZYL) METHYLENDITHIOCARBAZONE NICKEL(II) COMPLEX

The novel adducts of chelating diamines to the diamagnetic, square pla nar nickel(II) complex a-N-(4-dimethylaminobenzyl)methylendithiocarbaz one nickel(II) [hereafter abbreviated Ni(SN)(2)] have been prepared an d characterized, where the chelating diamines are 1,10-phenanthroline (phen), 2,2'-bipyridine (bipy), 5-nitro-1,10-phenanthroline (NO(2)phen ), 4,4'-methyl-2,2'-bipyridine (Mebipy) and 4,5-diazafluren-9-one (dia fo). The addition equilibrium constants (K), determined by a UV-vis sp ectrometer, were influenced by the coordinating ability of the added l igands in the order: K-phen > K-mebipy > K-bipy > K-NO2phen > K-diafo. The single crystal structure of the phenanthroline adduct was determi ned to study the possible of the addition processes. The coordination geometry of the nickel atom is distorted octahedral. The four nitrogen atoms of the two SN ligands and the phenanthroline molecule form the equatorial plane with a Ni-N distance ca 2.10 Angstrom and the two sul fur atoms site at the axial positions with the Ni-S distance of 2.40 A ngstrom. From the results of structural determination and the addition equilibrium studies, the possible addition mechanisms have been discu ssed. (C) 1997 Elsevier Science Ltd.