Exploring the properties of mixed valence cyanide bridged dinuclear complexes: Solvent stabilization of electronic isomers

MELINA B. ROSSI; PABLO ALBORÉS; LUIS M. BARALDO

INORGANICA CHIMICA ACTA

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2011 vol. 374 p. 334 - 340

0020-1693

We report here the synthesis and properties of a family of mixed-valence cyanide-bridged dinuclear complex ions trans-[(L1(L)4RuII(μ-NC)FeIII(CN)5]- (with L = pyridine or 4-dimethylaminopyridine (dmap) and L1 = pyridine, 4-methoxypyridine (meopy) or 4-dimethylaminopyridine)) whose properties could be adjusted smoothly by changing the acceptor properties of the solvent and the sigma donor properties of the L' pyridine ligand. In solution these complexes exhibit an intense solvent-dependent MMCT (RuII → FeIII) absorption in the near infrared region. Analysis of this band in different complexes and solvents suggests an enhanced interaction as the energies of the metal centers come closer. From this trend the anion trans-[(dmap)5Ru(μ-NC)Fe(CN)5]− (dmap = 4-dimethylaminopyridine) in water is expected to belong to the class II-III, but its spectral properties indicates a ground state with Ru(III)-Fe(II) character. The stabilization of this electronic isomer is probably related to the better donor properties of the hexacyanoferrate(II) moiety and its stronger interaction with water.