Ruthenium carbene complexes featuring a tridentate pincer-type ligand

Ruthenium carbene complexes featuring the bulky tridentate N,N'-bis(2,6-diisopropylphenyl)-2,6-pyridinedicarboxamido pincer-type ligand and different stabilizing phosphine ligands were synthesized and characterized. Preliminary results for the application to ring-closing metathesis show low activity for the cyclization of 1,7-octadiene with benzylidene(triphenylphosphine) [N,N'-bis(2,6-diisopropylphenyl)-2,6-pyridinedicarboxamido-kappa O-3,N,O/O,N,N]-ruthenium(II)(4a,b). Benzylidene(tricyclohexylphosphine)[N,N'-bis(2,6-diisopropylphenyl)-2,6-pyridinedicarboxamido-kappa O-3,N,O]ruthenium(II) (5) successfully transformed 1,7-octadiene to cyclohexene and ethylene in good yields at room temperature or 80 degrees C.