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

New ruthenium benzylidene complexes (3) bearing N-heterocyclic carbene and chelating phosphino-carboxylate ligands were easily prepared by the reaction of (H2IMe)(PPh3)(Cl)2RuCHPh (1) [H2IMe = 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.

Graphical abstractThe synthesis, characterization, and ring-closing metathesis (RCM) activity of new ruthenium benzylidene complexes bearing N-heterocyclic carbene and chelating phosphino-carboxylate ligands are presented. Catalysts featuring a five-membered or rigid six-membered chelating ring proved to exhibit enhanced stability and high catalytic efficiency toward the RCM reactions of diethyl diallylmalonate and diallylmalononitrile, especially at increased temperature. Figure optionsDownload full-size imageDownload as PowerPoint slide