Stability sequences of cadmium(II) and zinc(II) monohalide complexes in alcohols and binary solvent mixtures containing methanol, dimethylsulfoxide, acetonitrile and water

Abstract

Classification schemes, such as Ahrland's ‘a’-‘b’ organization of ligand acceptors, are important to the systemization of coordination chemistry. Aside from Ahrland's extensive studies in dimethylsulfoxide, little is known about the effects of solvent choice upon acceptor classification. Furthermore, there is a dearth of information about the behavior of fluoride complexes under non-aqueous conditions due to the lack of a suitable measurement technique for such studies. This renders previous halide studies incomplete, since the hardest ligand has been systematically excluded. We report the results of potentiometric studies of the stabilities of monohalide complexes (F −, Cl −, Br −) of cadmium(II) and zinc(II) in methanol, ethanol and binary solvent mixtures such as methanol/water, dimethylsulfoxide/ methanol, dimethylsulfoxide/water and acetonitrile/ water. This data provides important new information related to non-aqueous behavior of these d 10 acceptors, particularly with respect to solvent-related stability sequence changes previously reported for cadmium(II).