Synthesis and characterization of ruthenium(II) complexes with dendritic N-heterocyclic carbene ligands

Ru(II) complexes with a N-heterocyclic carbene ligand bearing flexible zeroth-, first-, or second-generation dendritic moieties were synthesized and characterized. The structure of the ruthenium complex with the zeroth-generation dendritic moieties was determined by X-ray crystallography. ONIOM calculations showed that the second generation dendritic moieties surrounded the ruthenium core. These complexes worked as active catalysts for the ring-closing metathesis at 25 °C.