Ruthenium complexes, their use in the metathesis reactions, and a process for carrying out the metathesis reaction

A complex of the general formula 1:

• wherein,
• X is an anionic ligand;
• Y is oxygen;
• L1 is a neutral ligand other than an N-heterocyclic carbene ligand;
• L2 is an N-heterocyclic carbene ligand;
• R1 is hydrogen, —C1-20 alkyl, —C2-20 alkenyl, —C2-20 alkynyl or —C5-10 aryl;
• and
• R2, R3, R4 and R5 are independently hydrogen, halo, C1-C16 alkyl, C1-C16 alkoxy, C1-C16 perfluoroalkyl, C3-C7 cycloalkyl, C2-C16 alkenyl, C5-C14 aryl, C5-C14 perfluoroaryl, C3-C12 heterocyclyl, —OR6, —NO2, —COOH, —COOR6, —CONR6R7, —SO2NR6R7, —SO2R6, —CHO, —COR6, wherein R6 and R7 are independently C1-C6 alkyl, C1-C6 perfluoroalkyl, C5-C14 aryl, C5-C14 perfluoroaryl;
• or R2, R3, R4 and R5 may be optionally joined together to form a substituted or unsubstituted, fused carbocyclic C4-8 ring, or a substituted or unsubstituted, fused aromatic ring.