The synthesis and characterisation of bis(phosphane)-linked (eta(6)-p-cymene)ruthenium(II)-borane compounds

The reaction of [(η6-p-cymene)RuCl2]2 with some bis(phosphane) ligands (dppm, dppe, dppv, dppa, dpp14b, dppf) has been investigated. In general mixtures of products were obtained, although the pendant phosphane complexes [(η6-p-cymene)RuCl2(η1-dppv)] and [(η6-p-cymene)RuCl2(η1-dppa)] were isolated and characterized in the solid state by X-ray diffraction. The later complex was obtained in lower yield and undergoes an equilibration reaction resulting in the formation of a dimeric species, where the dppa bridges two ruthenium centres, and uncoordinated phosphane; the bridging species was also structurally characterised in the solid state. In contrast, the reaction of [(η6-p-cymene)RuCl2(PPh3)] with dppa in the presence of [NH4]PF6 results in the formation of [(η6-p-cymene)RuCl(PPh3)(η1-dppa)]PF6, which is stable in solution. A series of linked ruthenium-borane complexes, viz. [(η6-p-cymene)RuCl2(η1-phosphane-BH3)] (phosphane = dppm, dppe, dppv, dppa, dpp14b, dppf) and [(η6-p-cymene)RuCl(PPh3)(η1-dppa-BH3)]PF6 have been prepared from isolated pendant phosphane complexes, those generated in situ, or from a preformed phosphane-borane adduct. The solid-state structures of [(η6-p-cymene)RuCl2(η1-dppm-BH3)], [(η6-p-cymene)RuCl2(η1-dppe-BH3)] and [(η6-p-Cymene)RuCl2(η1-dppv-BH3)] have been determined by X-ray diffraction analysis.