Synthesis, characterization and catalytic activity for ring-closing metathesis of ruthenium benzylidene complexes bearing N-heterocyclic carbene and bidentate phosphino-carboxylate ligands

Abstract

New ruthenium benzylidene complexes ( 3) bearing N-heterocyclic carbene and chelating phosphino-carboxylate ligands were easily prepared by the reaction of (H 2IMe)(PPh 3)(Cl) 2Ru CHPh ( 1) [H 2IMe = 1,3-bis(2,6-dimethylphenyl)-4,5-dihydroimidazol-2-ylidene] with corresponding phosphino-carboxylates 2. Catalysts featuring a five-membered or rigid six-membered chelating ring proved to exhibit enhanced stability and high catalytic efficiency toward the ring-closing metathesis (RCM) reaction of diethyl diallylmalonate and diallylmalononitrile.