Ligand Field Stabilization Energies of the Hexaaqua 3+ Complexes of the First Transition Series.

Abstract

An analysis of the ligand field stabilization energy which makes allowance for the nephelauxetic effect is shown to give satisfactory results when applied to the hydration enthalpies of the hexaaqua 3+ complexes of the first transition series. The contribution from the nephelauxetic effect is substantial, and the baseline for zero ligand field stabilization energy is displaced below the d(0) point. In these respects, the complexes show a closer resemblance to the hexafluorometalates(III) than to the hexaaqua 2+ ions. In the course of the analysis, the electronic spectra of the cesium alums of vanadium(III), manganese(III), and cobalt(III) are reexamined, and thermodynamic properties of particular complexes are calculated. These include Delta(Ti(3+),aq), E(&crclbr;)(Ti(3+)|Ti(2+)), and the relative stabilities of the high- and low-spin states of Co(3+)(aq), Mn(3+)(aq), and Cr(2+)(aq). The general influence of ligand field stabilization energies on redox potentials is also discussed.