Aqua ions.: 1.: The structures of the [Ru(OH2)6]3+ and [V(OH2)6]3+ cations in aqueous solution:: An EPR and UV-Vis study

Spectroscopic data are presented for the [V(OH2)(6)](3+) and [Ru(OH2)(6)](3+) cations, from which inferences are drawn regarding their structures in aqueous solution. EPR and absorption spectra of solutions and glasses are supplemented by spectra of the aqua ions in various crystalline environments, and the electronic and molecular structures interrelated through elementary angular overlap model calculations. It is concluded that in aqueous solution the [Ru(OH2)(6)](3+) cation is localized in the all-horizontal D-3d geometry, whereas the structure of the [V(OH2)(6)](3+) cation is close to T-h symmetry. These results are consistent with the most energetically favored geometries predicted by ab initio calculations.