SPECTROSCOPIC STUDIES OF EXCHANGE INTERACTIONS IN POLYNUCLEAR TRANSITION METAL COMPLEXES I. [(NH3)5Cr(OH)Cr(NH3)5] Cl5,3H20.

Abstract

Large single crystals of ,u-hydroxo-bis[pentaamminechromium(III) chloride trihydrate have been prepared and their spectroscopic properties determined. The analysis of polarized single-crystal luminescence spectra provides an accurate ground electronic level scheme for the weakly coupled chromium ions in the dimeric cluster. The splitting is described by the isotropic Hamiltonian X = JS,.Sb-j(S,.Sb)2 with J = 31.9 cm-1 and j = 0.23 cm-1. The temperature dependence of the polarized absorption spectrum is consistent with this level scheme. The positions of the components of the singly excited (4A2-2E) state have been determined.