A catalytic system comprising: (a) a precatalyst comprising: (i) a ruthenium metal, (ii) at least one multidentate Schiff salicylaldimine base ligand comprising an imino group and being coordinated to the metal, in addition to the nitrogen atom of said imino group, through at least one further oxygen atom ligated to said metal, (iii) a nucleophilic carbene ligand ligated to said metal, wherein the nucleophilic carbene ligand is selected from the group consisting of substituted or unsubstituted, saturated or unsaturated 1,3 diheteroatomic cyclic compounds, wherein the heteroatoms are nitrogen atoms, (iv) a carbon-containing ligand ligated to said metal, wherein said carbon-containing ligand is phenylindenylidene; (v) optionally, an anionic ligand different from the Schiff base ligand (ii), (b) a precatalyst activator wherein the precatalyst activator is selected from chlorosilanes having the formula SiCl 3 R, wherein R is selected from the group consisting of hydrogen, C 1 -C 20 alkyl, C 1 -C 20 heteroalkyl C 1 -C 20 alkoxy, aryl, aryloxy and heteroaryl, and (c) an inhibitor, wherein the inhibitor is selected from the group consisting of phosphites having formula P(OR 1)(OR 2)(OR 3) where R 1, R 2, R 3 may be the same or different and are each selected from the group consisting of hydrogen, C 1 -C 20 alkyl, C 1 -C 20 heteroalkyl, C 1 -C 20 alkoxy and aryl optionally substituted with one or more moieties selected from the group consisting of C 1 -C 20 alkyl, C 1 -C 20 heteroalkyl, C 1 -C 20 alkoxy, aryl, aryloxy, heteroaryl, heterocycloalkyl, disulfide, carbonate, isocyanate, carbodiimide, carboalkoxy, carbamate, halogen, thioether, ketone, aldehyde, ester, ether, amine, amide, nitro and carboxylic acid, the non-hydrogen groups optionally substituted with one or more moieties selected from the group consisting of C 1 -C 20 alkyl, C 1 -C 20 alkoxy and aryl, wherein the molar ratio of phosphite/ruthenium is in the range of 0.01 to 300 and wherein the molar ratio of phosphite/activator is 0.007 to 1000. (a) a precatalyst comprising: (i) a ruthenium metal, (ii) at least one multidentate Schiff salicylaldimine base ligand comprising an imino group and being coordinated to the metal, in addition to the nitrogen atom of said imino group, through at least one further oxygen atom ligated to said metal, (iii) a nucleophilic carbene ligand ligated to said metal, wherein the nucleophilic carbene ligand is selected from the group consisting of substituted or unsubstituted, saturated or unsaturated 1,3 diheteroatomic cyclic compounds, wherein the heteroatoms are nitrogen atoms, (iv) a carbon-containing ligand ligated to said metal, wherein said carbon-containing ligand is phenylindenylidene; (v) optionally, an anionic ligand different from the Schiff base ligand (ii), (i) a ruthenium metal, (ii) at least one multidentate Schiff salicylaldimine base ligand comprising an imino group and being coordinated to the metal, in addition to the nitrogen atom of said imino group, through at least one further oxygen atom ligated to said metal, (iii) a nucleophilic carbene ligand ligated to said metal, wherein the nucleophilic carbene ligand is selected from the group consisting of substituted or unsubstituted, saturated or unsaturated 1,3 diheteroatomic cyclic compounds, wherein the heteroatoms are nitrogen atoms, (iv) a carbon-containing ligand ligated to said metal, wherein said carbon-containing ligand is phenylindenylidene; (v) optionally, an anionic ligand different from the Schiff base ligand (ii), (b) a precatalyst activator wherein the precatalyst activator is selected from chlorosilanes having the formula SiCl 3 R, wherein R is selected from the group consisting of hydrogen, C 1 -C 20 alkyl, C 1 -C 20 heteroalkyl C 1 -C 20 alkoxy, aryl, aryloxy and heteroaryl, and (c) an inhibitor,