Highly coupled mixed-valence dinuclear ruthenium and osmium complexes with a bis-cyclometalating terpyridine analog as bridging ligand

• Published in: Inorganic chemistry Vol. 32; no. 21; pp. 4539 - 4543
• Main Authors: Beley, Marc, Collin, Jean Paul, Sauvage, Jean Pierre
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.10.1993
• Subjects: 140505 - Solar Energy Conversion- Photochemical, Photobiological, & Thermochemical Conversion- (1980-); 250903 - Energy Storage- Batteries- Materials, Components, & Auxiliaries; 400201 - Chemical & Physicochemical Properties; 400400 - Electrochemistry; ABSORPTION SPECTROSCOPY; AROMATICS; CHEMISTRY; COMPLEXES; Coordination compounds; ELECTROCHEMISTRY; ELECTRONIC STRUCTURE; ENERGY STORAGE; Exact sciences and technology; Inorganic chemistry and origins of life; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; OSMIUM COMPLEXES; Preparations and properties; RUTHENIUM COMPLEXES; SOLAR ENERGY; SPECTROSCOPY; TRANSITION ELEMENT COMPLEXES; VOLTAMETRY; Cationic complex; Divalent metal Complexes; Mixed oxidation number; Nitrogen heterocycle; Organic ligand; Stability constant; Transition metal Complexes; Cyclic voltammetry; Mu complex; Electrochemical properties; Complexes Mixed; Dinuclear complex; Ultraviolet visible spectrum; Platinoid Complexes; Oxidation; Infrared spectrum; Osmium II Complexes; Ruthenium II Complexes
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic00073a012

Long-range electron transfer and photoinduced charge separation are essential processes related to the development of molecular electronic and solar energy conversion devices. The dinuclear complexes (tterpy)M(typbp)M(tterpy)[sup 2+] (M = Ru(II) or Os(II), tterpy = 4[prime], -p-tolyl-2,2[prime]:6[prime], 2[close quotes]-terpyridine, tpbpH[sub 2] = 3,3[prime],5,5[prime]-tetrapyridylbiphenyl) have been prepared by oxidative coupling of the corresponding monomers M(tterpy)(dpb)[sup +] (dpbH = 1,3-di-o-pyridylbenzene). Spectrochemical and electrochemical properties of the monomers and dimers in different oxidation states are described. Chemical or electrochemical oxidation of the M(II)-M(II) species leads to the mixed-valence M(II)-M(III) dimer. The comproportionation constants K[sub c] determined by cyclic voltammetry (600 and 100 for Ru and Os, respectively) reflect the high stability of the M(II)-M(III) states. In addition, the near-infrared spectrum of each mixed-valence ion exhibits a very intense intervalence transfer (IT) transition. Although the two metal centers are separated by a large distance (11 [angstrom]), the matrix elements V[sub ab] are relatively large (0.15 and 0.12 eV for Ru and Os, respectively). This demonstrates the surprisingly high coupling ability of the bis-cyclometalating bridging ligand tpbp[sup 2[minus]].