Influence of ligand substitution at the donor and acceptor center on MMCT in a cyanide-bridged mixed-valence system.

We detail the rational design of bimetallic cyanide-bridged complexes [TpmRu(L)(μ-CN)Ru(L)Cp*][PF] (Tpm = Tris(1-pyrazolyl)methane, L = 1,10-phenanthroline (phen), 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (dbpy), L = bis(diphenylphosphino)methane (dppm), bis(diphenylphosphino)ethane (dppe), Cp* = 1,2,3,4,5-pentamethylcyclopentadiene). The metal-to-metal charge transfer (MMCT) properties of these one-electron oxidized complexes were investigated, suggesting that the substitution of the ancillary ligand provides a strong impetus to systematically tune the MMCT properties. The investigation results indicate that all the mixed-valence complexes belong to Class II mixed-valence complexes, according to the Robin-Day classification.