Reactions of metal ions with triketones in solution. Part IV. Kinetics and mechanisms of the reactions of nickel(II) and cobalt(II) with 2-aceto-1,8-dihydroxynaphthalene, 2,2′-dihydroxybenzophenone and 1,5-diphenylpentane-1,3,5-trione in methanolwater (70:30 v/v) solution

Abstract

The kinetics and mechanisms of the reactions of nickel(II) and cobalt(II) with 2-aceto-1,8-dihydroxynaphthalene (H 2adhna), 2,2′-dihydroxybenzophenone (H 2dhbpo) and 1,5-diphenylpentane-1,3,5-trione (H 2dppto) have been investigated in methanolwater solutions (70:30 v/v) at 25 °C and ionic strength 0.5 mol dm −3 NaClO 4. The formation reactions of the 1:1 complexes of both metal ions with H 2adhna and H 2dppto were investigated while in the case of H 2dhbpo only the reaction with nickel(II) could be investigated. The dimerization reactions of [M(Hadhna) + (M 2+ = Ni 2+, Co 2+) and [Ni(Hdhbpo)] + to form the 2:2 complexes were also investigated. Detailed mechanisms are proposed which account satisfactorily for the kinetic data.