Synthesis, Spectroscopic and Electrochemical Characterization and Molecular Structure of Polypyridyl Ruthenium Complexes Containing 4,4'-azobis(pyridine)

POURRIEUX, GASTON; FAGALDE, FLORENCIA; KATZ, NÉSTOR E.; PARELLA, TEODOR; BENET-BUCHHOLZ, JORDI; LLOBET, ANTONI

POLYHEDRON

Elsevier Science Ltd.

Lugar: Amsterdan, Holanda; Año: 2008 vol. 27 p. 2990 - 2996

0277-5387

New coordination compounds of formulae: [Ru(trpy)(bpy)(4,4’ -azpy)]2+, 1, [Ru(tpm)(bpy)(4,4’-azpy)]2+, 2, [(trpy)(bpy)Ru(4,4’-azpy)Ru(NH3)5]4+, 3, and [(trpy)(bpy)Ru(4,4’-azpy)Ru(bpy)(trpy)]4+, 5, with trpy = 2,2’:6’,2”-terpyridine, tpm = tris(1-pyrazolyl)methane), bpy = 2,2’-bipyridine and 4,4’-azpy = 4,4’- azobis(pyridine), have been synthesized as PF6- salts and characterized by spectroscopic and electrochemical techniques. The structure of the cation [Ru(trpy)(bpy)(4,4’-azpy)]2+ has been determined by X-ray diffraction analysis, which reveals a trans-configuration of coordinated 4,4’-azpy and a packing structure that is based on extensive p-interactions within neighboring molecules. Upon controlled potential electrolysis of the dinuclear [RuII,RuII] complex 3, a stable [RuII, RuIII] mixed-valent species, 4, was detected. From spectral data and Gaussian deconvolution analysis of the intervalence transition in 4, a strong electronic interaction between both ruthenium centers is disclosed (HAB = 550 cm-1), pointing to possible applications of 4,4’-azpy as a conducting bridge in ‘‘molecular wires”.