“…Previous studies on rhenium diimine complexes have indicated typical shifts from ca. −2 to −12 cm –1 for ligand-centered π,π* states, ,, while a shifts from −18 to −27 cm –1 have been reported for electrochemically reduced Re(CO) 3 Cl(bpy) and related complexes. − Therefore, in the case of R = t Bu in CH 2 Cl 2 , the shift observed for state I (−21 cm –1 ) is more consistent with an excited state in which the bpy moiety is reduced and the HBC acts as an electron donor, while state II (−7 cm –1 ) is consistent with a π,π* state with overlapping donor and acceptor, located on the bpy, HBC, or both. Similar trends are observed for most of the solvent systems, with some changes in the magnitude of the shifts.…”