Thermodynamic data for addition of bases to low-spin planar nickel(II) complexes with four sulphur-donor atoms

Abstract

Thermodynamic data have been obtained for the addition of two molecules of pyridine or 4-methyl-pyridine to bis(perthiobenzoato)nickel(II), bis(dithiobenzoato)nickel(II) and bis(dibenzyldithiocarb- amato)nickel(II) in benzene solution. Together with previously published data for addition of bases to nickel(II) xanthates and dithiophosphates, these results show that the variation of base adduct stabilities of NiS₄ complexes with four-membered chelate rings is due primarily to entropy effects. Possible origins for these effects are discussed.