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.