Isolation and characterization of a monomeric, solvent coordinated ruthenium(II)carbene cation relevant to olefin metathesis

The isolation as well as spectroscopic and structural characterization of [(κ2-tBu2PCH2PtBu2)ClRuCHCHC(CH3)2(CH3CN)]+ ([5+]), a solvent-coordinated monomeric ruthenium(II)carbene cation with a rigid cis-stereochemistry of two phosphines, are reported. Its relevance for the mechanism of olefin metathesis catalyzed by such complexes is discussed and distinct differences compared to complexes with the usual trans-phosphine stereochemistry are noted.