Solvent control of orbital mixing and electronic coupling in Ligand-Bridged mixed-valence complexes: Evidence for an intervalence hole-transfer pathway

Solvent-induced electronic effects exist for intervalence charge-transfer reactions involving complexes of the type (2,2′-bipyridine)₂ClRu^II(pyrazine)Ru ^III(NH₃)₄L⁴⁺, where L = NH₃ or various pyrazyl, pyridyl, or polypyridyl ligands. Specifically the following are found: (1) Mixing between appropriate donor and acceptor metal orbitals can be influenced substantially by the nature of the solvent. (2) The metal-metal interaction energy, H₁₃, is also affected. (3) From the solvent effects, intervalence transfer appears to follow (in part) a hole-transfer pathway.