Hydration and Solvation of Metal Ions

This chapter summarizes the experimentally reported structures of hydrated and solvated metal ions in solution and the solid state. The oxygen donor solvents dimethylsulfoxide, N,N-dimethylformamide, and N,N′-dimethylpropyleneurea and the nitrogen donor solvents acetonitrile and liquid ammonia have been selected because a relatively large number of solvate structures, in both the solid state and solution, have been reported. Their bonding characteristics are fairly different and can therefore act as models for a wide range of solvents. N,N′-Dimethylpropyleneurea is selected as it is space-demanding upon coordination forcing many metal ions to adopt lower coordination numbers than for most oxygen donor solvents. The physico-chemical impact of a lower coordination number with low symmetry is discussed. Liquid ammonia is representative for solvents with a strong electron-pair donor ability, and the impact on the coordination chemistry is discussed.