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.