STRUCTURAL, SPECTROSCOPIC AND REDOX STUDIES OF MER-[RUX3L3] (L=PME2PHOR ASME2PH, X=CL OR BR) - CRYSTAL-STRUCTURES OF MER-[RUX3(ASME2PH)(3)] (X=CL OR BR) AND [RU2X5(EME2PH)(4)] (X=BR, E=P OR AS, X=I, E=AS)

The complexes mer-[RuX3L3] (X = Cl or Br, L = PMe2Ph or AsMe2Ph) have been re-examined and assignments for their UV/VIS spectra proposed. At tempts to prepare analogues with X = I or L = SbR3 have been unsuccess ful. Cyclic voltammetry revealed only irreversible oxidation and reduc tion processes and chemical oxidation with halogens resulted in decomp osition to [RuX6](2-), in contrast to the chemistry of related osmium compounds. The crystal structures of mer-[RuX3(AsMe2Ph)(3)] (X = Cl or Br) have been determined and confirm the geometrical isomer formed. C rystal structures were also determined for [Ru2X5L4] (X = Br, L = PMe2 Ph or AsMe2Ph; X = I, L = AsMe2Ph) obtained by decomposition of mer-[R uX3L3] in solution, which are the first structurally characterised exa mples of Ru-2(5+) dimers of this type with bromide or iodide co-ligand s. The structures are consistent with a formal Ru-Ru bond order of 1/2 .