Excited states of transition metal compounds: Quantum chemistry of relaxation effects

The electronic excitation of coordination compounds is followed by a number of relaxation effects (geometry changes, emission, nonradiative transitions, electron transfer). This article concerns the possible ways to use the standard methods of modern quantum chemistry in conjunction with the time-dependent formalism (wave packets dynamics) to study these effects in the metal-to-ligand charge transfer (MLCT) excited states. The first example concerns the estimation of the geometry changes in organic ligands due to the electronic excitation. The second example concerns the prediction of the trends in the constants of nonradiative transitions. The results of the calculations for several sets of Ru(II) and Os(H) complexes with 2,2'-bipyridine and its derivatives are in good agreement with experiment. (C) 2003 Wiley Periodicals, Inc.