Synthesis, characterization and olefin metathesis studies of a family of ruthenium phosphonium alkylidene complexes

The synthesis of four ruthenium phosphonium alkylidene complexes [(H2IMes)Cl2Rudouble bond; length as m-dashCH(PCy3)]+[A]− (1, A = B(C6F5)4; 2, A = BF4; 3, A = OTf; 4, A = BPh4), differing only in the anion is described. The X-ray structures of 1, 3 and 4 show them to be isostructural in the cation, with no interaction between the Ru centers and the anion. Ring closing metathesis of a substrate to a six-membered methylcyclohexene at 0 °C in CD2Cl2 using 1 mol% catalyst, shows that catalysts 1–4 behave very similarly, and exhibit superior activity in comparison to Grubbs second generation and fast-initiating catalysts.