| abstract |
The invention relates to an N-heterocyclic carbene complex of general formulas I to IV (I) (II) (III) (IV), according to which A1 stands for NR2 or PR2, A2 stands for CR2R2', NR2, PR2, O or S, A3 stands for N or P, and C stands for a carbene carbon atom, ring B is an unsubstituted or a mono or poly-substituted 5 to 7-membered ring, substituents R2 and R2' stand, inter alia, for a linear or branched C1-C10-alkyl group and, if A1 and A2 each stand for NR2 or PR2, are the same or different, M in formulas I, II, III or IV stands for Cr, Mo or W, X1 or X2 in formulas I to IV are the same or different and represent, inter alia, C1-C18 carboxylates and C1-C18-alkoxides, Y is inter alia oxygen or sulphur, Z is inter alia a linear or branched C1-C10-alkylenoxy group, and R1 and R1' in formulas I to IV are, inter alia, an aliphatic or aromatic group. These compounds are particularly suitable for use as catalysts for olefin metathesis reactions and have the advantage, compared to known Schrock carbene complexes, of displaying clearly increased tolerance to functional groups such as, in particular, aldehydes, secondary amines, nitriles, carboxylic acids and alcohols. |