| abstract |
The invention relates to a complex of ruthenium of the structural formula I, n n n where X 1 and X 2 are identical or different and are each an anionic ligand, n R 1 and R 2 are identical or different and can also contain a ring, and R 1 and R 2 are each hydrogen or/and a hydrocarbon group, n the ligand L 1 is an N-heterocyclic carbene and the ligand L 2 is an uncharged electron donor, in particular an N-heterocyclic carbene or an amine, imine, phosphine, phosphite, stibine, arsine, carbonyl compound, carboxyl compound, nitrile, alcohol, ether, thiol or thioether, n where R 1 , R 2 , R 3 and R 4 are hydrogen or/and hydrocarbon groups. n The invention further relates to a process for preparing acyclic olefins having two or more carbon atoms or/and cyclic olefins having four or more carbon atoms from acyclic olefins having two or more carbon atoms or/and from cyclic olefins having four or more carbon atoms by an olefin metathesis reaction in the presence of at least one catalyst, wherein a complex is used as catalyst and R′ 1 , R′ 2 , R′ 3 and R′ 4 are hydrogen or/and hydrocarbon groups. |