Coordination behavior of some bridge ligands having S–O bond bound to four-membered ring unit (Ru2O2) of dinuclear areneruthenium complexes

Visible light irradiation of cis-azobenzene bridging dinuclear η6-areneruthenium complex [Ru2(η6:η1-C6H5CH2CH2CH2O)2(cis-PhN = NC6H4OMe-p)](BF4)2 in the presence of excess DMSO led to precipitation of a new dinuclear complex containing 1 equiv. DMSO ligand, [Ru2(η6:η1-C6H5CH2CH2CH2O)2(DMSO)](BF4)2 (6). A single crystal X-ray structural study of 6 revealed the presence of bridging DMSO ligand which uses O and S atoms as the donor. Treatment of 6 with 1 and 2 equiv. NaBArf (BArf = B[C6H3(CF3)2-2,5]4) afforded [Ru2(η6:η1-C6H5CH2CH2CH2O)2(DMSO)](BF4)(BArf) and [Ru2(η6:η1-C6H5CH2CH2CH2O)2(DMSO)](BArf)2, respectively, although the former was not isolated but assumed to exist only in solution by conductivity measurements. A neutral dinuclear areneruthenium complex with a bridging SO42- ligand, [Ru2(η6:η1-C6H5CH2CH2CH2O)2(SO4)] was prepared from the hydroxide [Ru2(η6:η1-C6H5CH2CH2CH2O)2(OH)]BF4 and [Et3NH](HSO4). The SO42- ion in this complex coordinates to dicationic Ru2 center rather strongly in CH2Cl2, while in MeOH the complex lies in equilibrium with a complex formed by methanolysis reaction, namely methoxy bridging dinuclear complex [Ru2(η6:η1-C6H5CH2CH2CH2O)2(OMe)]+(HSO4-).

The coordinatively unsaturated dinuclear areneruthenium dication having the tethered alkoxy donor binds the neutral, monoanionic and dianionic ligands with S–O bond which bridge over two ruthenium atoms. Some unique solution behavior of the bridge ligands has been discussed.Figure optionsDownload as PowerPoint slide