Solvent Effects on the ESR Spectra of Copper(II) Complexes. A Consideration of the Donicity of Water and Methanol

Abstract
Solvent effects on the ESR spectra of bis(2,6-dimethyl-3,5-heptanedionato)copper(II) ([Cu(dibm)2]) and a similar copper(II) complex were investigated in some detail. A clear relationship between the ESR parameters and the donicity of the solvents was confirmed, and this is discussed with the intention of investigating the donicities of water and methanol. The donor number for water in an aqueous solution was estimated to be about 30 from a precise analysis of the ESR spectra of [Cu(dibm)2] in water–methanol mixtures.