The Synthesis and Characterisation of Bis(phosphane)‐Linked ( 6 ‐ p ‐Cymene)ruthenium( II )–Borane Compounds

The reaction of [(η 6 ‐ p ‐cymene)RuCl 2 ] 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 [(η 6 ‐ p ‐cymene)RuCl 2 (η 1 ‐dppv)] and [(η 6 ‐ p ‐cymene)RuCl 2 (η 1 ‐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 [(η 6 ‐ p ‐cymene)RuCl 2 (PPh 3 )] with dppa in the presence of [NH 4 ]PF 6 results in the formation of [(η 6 ‐ p ‐cymene)RuCl(PPh 3 )(η 1 ‐dppa)]PF 6 , which is stable in solution. A series of linked ruthenium–borane complexes, viz. [(η 6 ‐ p ‐cymene)RuCl 2 (η 1 ‐phosphane‐BH 3 )] (phosphane = dppm, dppe, dppv, dppa, dpp14b, dppf) and [(η 6 ‐ p ‐cymene)RuCl(PPh 3 )(η 1 ‐dppa‐BH 3 )]PF 6 have been prepared from isolated pendant phosphane complexes, those generated in situ, or from a preformed phosphane–borane adduct. The solid‐state structures of [(η 6 ‐ p ‐cymene)RuCl 2 (η 1 ‐dppm‐BH 3 )], [(η 6 ‐ p ‐cymene)RuCl 2 (η 1 ‐dppe‐BH 3 )] and [(η 6 ‐ p ‐cymene)RuCl 2 (η 1 ‐dppv‐BH 3 )] have been determined by X‐ray diffraction analysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)