Solvent and phosphine dependency in the reaction of cis-RuCl2(P–P)2 (P–P = dppm or dppe) with terminal alkynes

Reaction of cis-[RuCl2(dppm)2] (dppm = 1,2-bis(diphenylphosphino)methane) with PhCtriple bond; length of mdashCH and NaPF6 utilising methanol as solvent results in the formation of the η3-butenynyl complex [Ru(η3-PhCtriple bond; length of mdashCsingle bondCdouble bond; length as m-dashCHPh)(dppm)2][PF6] in good yield. Similar reactions with ButCtriple bond; length of mdashCH and PrnCtriple bond; length of mdashCH resulted in the corresponding alkyl-substituted complexes and all three of these compounds have been characterised by NMR spectroscopy and X-ray crystallography. The mechanism of this reaction has been probed by employing labelling experiments with both PhCtriple bond; length of mdashCD and PhCtriple bond; length of mdash13CH allowing the identity of possible intermediates in the reaction to be determined. Furthermore, [Ru(η3-PhCtriple bond; length of mdashCsingle bondCdouble bond; length as m-dashCHPh)(dppm)2][PF6] has been shown to be an effective regio- and stereo-selective catalyst for the dimerisation of PhCtriple bond; length of mdashCH to Z-PhCtriple bond; length of mdashCsingle bondCHdouble bond; length as m-dashCHPh in the absence of solvent. In contrast, no evidence for the formation of alkyne coupling was obtained from the reaction of cis-[RuCl2(dppe)2] (dppe = 1,2-bis(diphenylphosphino)ethane) with PhCtriple bond; length of mdashCH and NaPF6.