SYNTHESIS, SPECTROSCOPIC, MAGNETIC, CONDUCTOMETRIC AND ELECTROCHEMICAL INVESTIGATIONS OF ICKEL(II)-1-PHENYL-4,6-DIMETHYLPYRIMIDINE-2-THIONECOMPLEXES

Tris-, bis- and mono-ligand complexes of Ni-II with 1-phenyl-4,6-dimet hylpyrimidine-2-thione (L) having the general formulae NiL(3)X(2) . 2H (2)O (X=ClO4-, BF4-), NiL(2)X(2) (X = Cl-, Br-, SCN- or NO3-), NiL(2)X (2) . EtOAc (X = Br- or I-), NiL(2)X(2) . H2O . EtOH (X = I- or NO3-) and NiLCl(2) . 3H(2)O, were synthesized and their structures deduced f rom i.r. and electronic spectra, and magnetic properties. The combined evidence is consistent with an octahedral coordination for the Ni-II ion in all the complexes, with the ligand acting as a bidentate N,S-ch elating agent. Spectral evidence, conductivity data and electrochemica l results in DMF solution show that the complexes undergo solvolysis r eadily. Polarographic and c.v. data for the [NiL(3)](ClO4)(2) . 2H(2)O complex and for the [Ni(DMF)(6)](ClO4)(2)-L systems, at increasing li gand concentrations, have shown that in DMF solution the [Ni(DMF)(6)]( 2+) cation prevails and that the thiopyrimidine-containing species, [N iL(DMF)(5)](2+) (L = N-monodentate ligand) (beta = 2.42 x 10(6)), can be formed only in the presence of a large excess of free ligand.