Vibrational satellite structures and properties of electronic states of transition metal complexes

Abstract Pd (2- thpy ) 2 , Pt (2- thpy ) 2 , [ Ru ( bpy-h 8 ) 3 ] 2+ , [ Ru ( bpy-h 8 ) 2 ( bpy-d 8 )] 2+ , [ Ru ( bpy-d 8 ) 3 ] 2+ , [ Os ( bpy-h 8 ) 3 ] 2+ , [ Os ( bpy-h 8 ) 2 ( bpy-d 8 )] 2+ , and [ Os ( bpy-d 8 ) 3 ] 2+ were isolated in crystalline matrices in order to obtain highly resolved emission spectra. A detailed analysis of the electronic origins and of the vibrational satellite structures reveals trends, which allow the various compounds to be ordered with respect to increasing MLCT character. Interestingly, an increasing MLCT character is connected with decreasing shifts of the equilibrium positions of the potential hypersurfaces and with decreasing changes of force constants upon excitation. Presumably, this behavior is a consequence of an increasing covalency in the compounds investigated. Moreover, especially the resolved vibrational satellite structures of [ Ru ( bpy ) 3 ] 2+ and [ Os ( bpy ) 3 ] 2+ allow the conclusion that the electronic excitation in the lowest excited states is delocalized over the metal and the three ( bpy )-ligands.