A comparison of ground- and excited-state properties of [Ru(bz)(2)](2+) and bis(eta 6-benzene) ruthenium(II) p-toluenesulfonate using the density functional theory

The ground- and excited-state properties of both [Ru(bz)(2)](2+) and crysta lline bis(eta(6)-benzene)ruthenium(II) p-toluenesulfonate are investigated using the density functional theory. A symmetry-based technique is employed to calculate the energies of the multiplet structure splitting of the sing ly excited triplet states. For the crystalline system, a Buckingham potenti al is introduced to describe the intermolecular interactions between the [R u(bz)(2)](2+) system and its first shell of neighbor molecules. The overall agreement between experimental and calculated ground- and excited-state pr operties is good, as far as the absolute transition energies, the Stokes sh ift, and the geometry of the excited states are concerned. The calculated d -d excitation energies of the isolated cluster are typically 1000-2000 cm(- 1) too low. An energy lowering is obtained in a(1g) --> e(1g) (E-3(1g)) exc ited state when the geometry of [Ru(bz)(2)](2+) is bent along the e(1u) Ren ner-Teller active coordinate. It vanishes as the crystal packing is taken i nto account. (C) 1999 John Wiley & Sons, Inc.