Chelating Carbene Ligand Precursors and Their Use in the Synthesis of Metathesis Catalysts

A chelating carbene complex of the formula:

• wherein
• X1 and X2 are each, independently, any anionic ligand;
• L1 is any neutral electron donor, and wherein any of two or three of X1, X2, and L1 may form a multidentate ligand;
• M is ruthenium or osmium;
• R5, R6, R7, and R8 are each, independently, selected from the group consisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, aryl, heteroaryl, alkoxy, alkenyloxy, aryloxy, alkoxycarbonyl, carbonyl, alkylamino, alkylthio, alkylsulfonyl, nitrile, nitro, alkylsulfinyl, trihaloalkyl, perfluoroalkyl, carboxylic acid, ketone, aldehyde, nitrate, cyano, isocyanate, hydroxyl, ester, ether, amine, imine, amide, sulfide, disulfide, sulfonate, carbamate, silane, siloxane, phosphine, phosphate, and borate, wherein any two of R5, R6, R7, and R8 may be independently connected through hydrocarbon or functionalized hydrocarbon groups forming an aliphatic or aromatic ring;
• Y is a heteroatom selected from oxygen (O), sulfur (S), nitrogen (N), or phosphorus (P);
• and
• Z is selected from the group consisting of hydrogen, alkyl, aryl, functionalized alkyl, and functionalized aryl where the functional group(s) may independently be one or more or the following:
• alkoxy, aryloxy, halogen, carboxylic acid, ketone, aldehyde, nitrate, cyano, isocyanate, hydroxyl, ester, ether, amine, imine, amide, sulfide, disulfide, carbamate, silane, siloxane, phosphine, phosphate, and borate.