Novel phospholyl(diphenylphosphino)methane-ruthenium complexes: unexpected non-assisted cis to trans isomerization of [RuCl2(κ2-P–P′)2]

Abstract

Using the unsymmetrical P–P′ phospholyl(phosphino)methane ligand, complex cis-[RuCl₂(κ²-P–P′)₂] is easily prepared from [RuCl₂(DMSO)₄]. The two phosphole-phosphorus atoms lie in the trans position to the two cis-chloro ligands. This complex slowly isomerizes spontaneously at 20 °C to the trans-[RuCl₂(κ²-P–P′)₂] diastereoisomer where the two phosphole moieties are mutually trans, as well as the two chloro ligands and the two Ph₂P moieties. DFT calculations show that this non-classical cis–trans isomerisation process requires a 3 kcal mol⁻¹ energy and involves the decoordination of a phosphole arm.