The structure of dimethylsulfoxide-solvated magnesium and calcium ions in solution and the solid state, and an overview of the coordination chemistry of hydrated and solvated alkaline earth metal ions

Abstract

The structures of dimethylsulfoxide-solvated magnesium and calcium ions have been studied in the solid state and in dimethylsulfoxide solution by X-ray crystallography and large-angle X-ray scattering (LAXS), respectively. The magnesium and calcium ions coordinate six dimethylsulfoxide molecules in both the solid state and solution with mean Mg–O and Ca–O bond distances in solid perchlorate salts of 2.062(4) and 2.303(5) Å, respectively. A summary of the coordination chemistry of the hydrated and solvated alkaline earth metal ions shows that beryllium(II) and magnesium ions are tetrahedral and octahedral, respectively, in all solvents studied, while calcium and strontium are eight-coordinated in square antiprismatic fashion in water, but octahedral in dimethylsulfoxide and other organic solvents. Mean M–O bond distances of the hydrated alkaline earth metal ions were used to calculate the ionic radii of the alkaline earth metal ions.