A Ru carbene (8, Scheme 2) that contains an internal metal-oxygen chelate is an active metathesis catalyst and is readily obtained by the sequential treatment of Cl2Ru(PPh3)(3) with (2-isopropoxyphenyl)-diazomethane and PCy3. This Ru-carbene complex offers excellent stability to air and moisture and can be recycled in high yield by silica gel column chromatography. The structures of this and related complexes have been unambiguously established by NMR and single-crystal X-ray diffraction studies.