Properties of ruthenium bipyridyl dimers bridged by disubstituted anthraquinones

Abstract

Ru(bpy) 2Cl 2 reacts with 1, 4-DHAQ, 1, 5-DHAQ and 1, 4-AHAQ to form dinuclear complexes. Its reaction with 1, 8-DHAQ produces a monomer. Both 1, 4-DHAQ and 1, 4-AHAQ produce stable mixed valence complexes when oxidized, and show greater separation of ruthenium oxidation potentials than the 1, 5-DHAQ complex. K c has been calculated to be 3.7 × 10 4 for the 1, 4-DHAQ complex, 1.3 × 10 8 for the 1, 4-AHAQ complex, and 3.4 × 10 2 for the 1, 5-DHAQ complex. In all cases E 1/2(1) for the dimers is less positive than E 1/2(1) for the monomeric 1, 8-DHAQ complex. Spectral studies of the mixed valence states showed IT bands at approximately 2000 nm in acetonitrile for the 1, 4-DHAQ complex and at 1368 nm in acetonitrile for the 1, 4-AHAQ complex. Solvent dependence was observed for the IT band for the latter complex. The experimental evidence indicates that the three dinuclear complexes may be class II mixed valence dimers.