Ruthenium cyclopentadienylidene phosphorane complexes – Synthesis, characterization and catalysis

The synthesis of ruthenium complexes of cyclopentadienylidene phosphorane ligands C5H3R1–PR22R3 (a: R1 = H, R2 = R3 = Ph; b: R1 = tBu, R2 = Ph, R3 = Me; c: R1 = H, R2 = R3 = nBu; d: R1 = H, R2 = Ph; R3 = NHDip with Dip = 2,6-diisopropylphenyl) is described. The influence of steric and electronic effects of these ligands on spectroscopic and structural properties is analyzed by means of NMR spectroscopy and x-ray crystallography. Complexes of the form [Ru(η5-C5H3R1–PR22R3)(NCMe)3] [PF6]23a–c are examined concerning their activity in a representative alkene-alkyne coupling reaction. The influence of the sterically demanding phosphonium ionic tag at the Cp-moiety on the yield and regioselectivity of the coupling of methyl 10-undecenoate with 1-octyne is investigated.