Synthesis and photochromic property of cis-azobenzene complex with a binuclear η6-areneruthenium(II) unit

A cis-azobenzene complex with a binuclear ruthenium(II) unit bridged by alkoxo ligands which are tethered to eta (6)-arene donors (4) was synthesized from corresponding binuclear acetonitrile complex (3) and trans-azobenzene irradiated by UV light (300 nm < < 400 nm). On irradiation with visible light ( > 510 nm) in acetonitrile, 4 mostly dissociated to transazobenzene and 3 with the photostationary ratio 3/4 = 92/8.