ELECTRON DELOCALIZATION AND LOCALIZATION IN MIXED-LIGAND [RU(LL)(N)(LL')(3-N)](2+) COMPLEXES

Highly resolved emission spectra of isolated [Ru(LL)(n)(LL')(3-n)](2+) complexes doped into [Zn(bpy)(3)](ClO4)(2) with LL and LL' representi ng the ligands bpy-h(8), bpy-d(8), and bpz are presented. The informat ion displayed in the electronic origins and the vibrational satellite structures combined with the emission decay behavior is used to provid e a clear distinction between localized and delocalized MLCT transitio ns to the lowest excited states. In particular, the appearance or nona ppearance of ligand-centered vibrational modes belonging to different types of ligands provides crucial evidence for delocalization or local ization. Thus, for a localized excitation in [Ru(bpy)(2)(bpz)](2+) onl y the ligand-centered modes of bpz can be found in the emission spectr a. In contrast, for [Ru(bpy-h(8))(2)(bpy-d(8))](2+) the ligand-centere d vibrations of bpy-h(8) and bpy-d(8) accompany the same electronic or igin. This is strong evidence for the delocalization of the excited el ectron in mixed-ligand [Ru(bpy-h(8))(2)(bpy-d(8))](2+). Consequently, the lowest MLCT excited states in homoleptic complexes like [Ru(bpy-h( 8))(3)](2+)and [RU(bpy-d(8))(3)](2+) are also delocalized over the met al and the different ligands.