Bridge coordination of bidentate ligands to a dinuclear η6-arene-ruthenium(II) unit constructed by a chelating and bridging alkoxo ligand

Dinuclear η6-areneruthenium(II) complex of the formula [Ru2{η6:η1:μ-C6H5(CH2)3O}2(μ-Cl)]+ (2) was prepared by treatment of Ru{η6-C6H5(CH2)3OH}Cl2 with base. X-Ray structure analysis revealed 2 to contain two Ru centers bridged by Cl ligand as well as by two alkoxo groups, which are tethered to η6-arene ligands. Treatment of 2 with Ag+ in acetonitrile afforded dicationic complex [Ru2{η6:η1:μ-C6H5(CH2)3O}2(CH3CN)2]2+ (3) in which two CH3CN ligands are located trans to each other with respect to the Ru2O2 plane. Irradiation with UV light (300–400 nm) of a CH3CN solution of 3 and trans-azobenzene gave cis-azobenzene complex [Ru2{η6:η1:μ-C6H5(CH2)3O}2(μ-cis-PhNNPh)]2+ (4). Cis-azobenzene ligand of 4 dissociated under irradiation of light (>510 nm) to give 3 in CH3CN or disulfide complex [Ru2{η6:η1:μ-C6H5(CH2)3O}2(μ-PhSSPh)]2+ (6) in the presence of the disulfide. X-ray structure determination of 4 and 6 established bridge coordination of cis-azobenzene and disulfide ligands. Reaction of 3 with pyridazine afforded similar dimeric complex [Ru2{η6:η1:μ-C6H5(CH2)3O}2(μ-pyridazine)]2+ (7), while the reaction with bipyridine afforded monomeric alkoxo chelate complex [Ru{η6:η1-C6H5(CH2)3O}(bipy)]+ (8).