Synthesis and characterization of dinuclear ruthenium(II) complexes with dianion of 2,5-dihydroxy-1 ,4-benzoquinone as bridging ligand

and [((Me2SO).~Ru} 2 (~-L)](Clh (where phen=l,lO-phenanthro­ line, py=pyridine, PPh3=triphenylphosphine, Me2SO=dimethyl­ sulphoxide and L=dianion of 2,5-dihydroxy-1 ,4-benzoquinone) have been synthesised and characterized by elemental analysis, IR, NMR and voltammetric studies. The chemistry of dinuclear complexes contammg polypyridyl-Ru(Il) has been evoking interest during the last two decades I-s. Dinuclear complexes containing polypyridyl Ru(II) fragments are of particular interest for the study of mixed valency because of their kinetic inertness in both the +2 and +3 oxidation states, generally reversible chemical behaviour, and good rr-donor ability which allows interaction with the bridging ligand orbitals 1 . Many of the ligands used in such binuclear complexes are polypyridyl based, and although significant metal­ metal interactions can occur via metal-ligand drr-rr * overlap, these may be limited by considerable energy gap between the ruthenium d(rr) and ligand based rr * levels 1 . Dioxolene based ligands, in contrast have orbital of 1t symmetry which are much closer in energy to those of metal based d(n:) orbitals, and recently much effort has been devoted to the study of the very rich electrochemical and spectroscopic properties of the mononuclear ruthenium complexes with a variety of dioxolene ligands 6 -R. Since strong metal-metal interactions in binuclear complexes are facilitated by electron delocalization from the metal towards the bridging ligands, binucleating bridging ligands based on dioxolene are excellent candidate for the preparation of such complexes