Magnetic interactions in dimeric transition metal complexes: Basic erythro-chromium(III)

First principles density functional theory is utilized to describe electron ic structure and magnetic interactions between Cr(III) ions in linear and b ent geometry of [cis-[hydroxotetramminechromium-mu-hydroxopentamminechromiu m](4+). The effective exchange parameter J is extracted and compared with e mpirical values fitted to experimental data. The calculated value J = 48 K for bent geometry compares well with the 30 K experimental value: the magne tic interaction is an order of magnitude larger in the linear configuration . Low-lying optical transitions are analyzed, making use of the transition state scheme, and are in semiquantitative agreement with experimental absor ption.