Nitrogen titanium complex having general formula (I): wherein: - R 1 represents a hydrogen atom; or is selected from linear or branched C 1 -C 20 alkyl groups, preferably C 1 -C 15 , optionally halogenated, cycloalkyl groups optionally substituted, aryl groups optionally substituted; - R 2 , R 3 , R 4 and R 5 , identical or different, represent a hydrogen atom; or are selected from linear or branched C 1 -C 20 alkyl groups, preferably C 1 -C 15 , optionally halogenated, cycloalkyl groups optionally substituted, aryl groups optionally substituted, nitro groups, hydroxyl groups, amino groups; - Y represents a NH-R 6 group wherein R 6 represents a hydrogen atom, or is selected from linear or branched C 1 -C 20 alkyl groups, preferably C 1 -C 15 , optionally halogenated, cycloalkyl groups optionally substituted, aryl groups optionally substituted; or a N-R 7 group wherein R 7 is selected from linear or branched C 1 -C 20 alkyl groups, preferably C 1 -C 15 , optionally halogenated, cycloalkyl groups optionally substituted, aryl groups optionally substituted; - X 1 , X 2 , X 3 and X 4 , identical or different, represent a halogen atom such as chlorine, bromine, iodine, preferably chlorine; or are selected from linear or branched C 1 -C 20 alkyl groups, preferably C 1 -C 15 , -OCOR 8 groups or groups - OR 8 wherein R 8 is selected from linear or branched C 1 -C 20 alkyl groups, preferably C 1 -C 15 ; or one of X 1 , X 2 and X 3 is selected from ethers such as diethylether, tetrahydrofuran (THF), dimethoxyethane, preferably is tetrahydrofuran (THF); - n is 1 in the case wherein Y represents a NH-R 6 group wherein R 6 has the same meanings reported above; or is 0 in the case wherein Y represents a N-R 7 group wherein R 7 has the same meanings reported above, or in the case wherein one of X 1 , X 2 and X 3 is selected from ethers. - R 1 represents a hydrogen atom; or is selected from linear or branched C 1 -C 20 alkyl groups, preferably C 1 -C 15 , optionally halogenated, cycloalkyl groups optionally substituted, aryl groups optionally substituted; - R 2 , R 3 , R 4 and R 5 , identical or different, represent a hydrogen atom; or are selected from linear or branched C 1 -C 20 alkyl groups, preferably C 1 -C 15 , optionally halogenated, cycloalkyl groups optionally substituted, aryl groups optionally substituted, nitro groups, hydroxyl groups, amino groups; - Y represents a NH-R 6 group wherein R 6 represents a hydrogen atom, or is selected from linear or branched C 1 -C 20 alkyl groups, preferably C 1 -C 15 , optionally halogenated, cycloalkyl groups optionally substituted, aryl groups optionally substituted; or a N-R 7 group wherein R 7 is selected from linear or branched C 1 -C 20 alkyl groups, preferably C 1 -C 15 , optionally halogenated, cycloalkyl groups optionally substituted, aryl groups optionally substituted; - X 1 , X 2 , X 3 and X 4 , identical or different, represent a halogen atom such as chlorine, bromine, iodine, preferably chlorine; or are selected from linear or branched C 1 -C 20 alkyl groups, preferably C 1 -C 15 , -OCOR 8 groups or groups - OR 8 wherein R 8 is selected from linear or branched C 1 -C 20 alkyl groups, preferably C 1 -C 15 ; or one of X 1 , X 2 and X 3 is selected from ethers such as diethylether, tetrahydrofuran (THF), dimethoxyethane, preferably is tetrahydrofuran (THF); - n is 1 in the case wherein Y represents a NH-R 6 group wherein R 6 has the same meanings reported above; or is 0 in the case wherein Y represents a N-R 7 group wherein R 7 has the same meanings reported above, or in the case wherein one of X 1 , X 2 and X 3 is selected from ethers. <EOS>