Influence of temperature and concentration upon nickel(II) chloride interactions in dimethyl sulphoxide

Abstract

The chloro-nickel(II) complexes obtained in dimethyl sulphoxide (DMSO) are described, viz., the octahedral complexes [NiCl(DMSO)₅]⁺ and [NiCl₂(DMSO)₄]⁰ and the tetrahedral complexes [NiCl₃(DMSO)]^– and NiCl₄^2–. It is shown that the tetrahedral species produced on warming a solution of NiCl₂ is [NiCl₃(DMSO)]^–, not NiCl₄^2– as previously claimed. The effect of temperature upon the various equilibria existing in solution at different Cl : Ni mole ratios is discussed and the effect of cation variation is noted. For the equilibrium [NiCl₂(DMSO)₄]⁰+ Cl^–⇌[NiCl₃(DMSO)]^–+ 3DMSO, ΔH was calculated to be +13·3 ± 0·3 kcal. mole^–1.