TRENDS IN METAL-LIGAND ORBITAL MIXING IN GENERIC SERIES OF RUTHENIUM N-DONOR LIGAND COMPLEXES-EFFECT ON ELECTRONIC-SPECTRA AND REDOX PROPERTIES

Generic series of complexes [Ru(bpy)(3-n)(LL)(n)](2+) (bpy = 2,2'-bipy ridine), where LL is a diimine ligand including specifically 2,2'-bipy razine (bpz), 2,2'-azobipyridine (abpy), and o-benzoquinonediimine (bq di), are studied with respect to their electrochemistry, optical spect roscopy and electronic structure as elucidated using Zerner's INDO/S m ethod. Characteristics of their electrochemistry and optical spectrosc opy are explained in terms of mixing between ruthenium d orbitals and diimine ligand pi and pi orbitals, increasing in importance from bpy to bpz to abpy to bqdi. In this last case, these species have characte ristics not unlike fully delocalized organic molecules. (C) 1998 Elsev ier Science S.A. All rights reserved.