Synthesis, spectroscopic, magnetic, conductometric and electro-chemical investigations of nickel(II)-1-phenyl-4,6-dimethylpyrimidine-2-thione complexes

Summary

Tris-, bis- and mono-ligand complexes of Ni^II with 1-phenyl-4, 6-dimethylpyrimidine-2-thione (L) having the general formulae NiL₃X₂·2H₂O (X = ClO ^p−_inf4 , BF ^p−_inf4 ), NiL₂X₂ (X = Cl⁻, Br⁻, SCN⁻ or NO ^p−_inf3 ), NiL₂X₂·EtOAc (X = Br⁻ or I⁻), NiL₂X₂·H₂O·EtOH (X = I⁻ or NO ^p−_inf3 ) and NiLCl₂·3H₂O, were synthesized and their structures deduced from 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-chelating agent. Spectral evidence, conductivity data and electro-chemical results in DMF solution show that the complexes undergo solvolysis readily. Polarographic and c.v. data for the [NiL₃](ClO₄)₂·2H₂O complex and for the [Ni-(DMF)₆](ClO₄)₂-L systems, at increasing ligand concentrations, have shown that in DMF solution the [Ni(DMF)₆]²⁺ cation prevails and that the thiopyrimidine-containing species, [NiL(DMF)₅]²⁺ (L = N-monodentate ligand) $(\beta = 2.42 \times 10^6 )$, can be formed only in the presence of a large excess of free ligand.