Bis-imine pyridine complex of lanthanides catalytic system comprising said bis-imine pyridine complex and process for the (co)polymerization of conjugated dienes

A bis-imine pyridine complex of lanthanides having general formula (I):

• wherein:
• Ln represents a metal of the series of lanthanides;
• R1 and R2, equal to or different from each other, represent a hydrogen atom;
• or they are selected from linear or branched C1-C20 alkyl groups, cycloalkyl groups optionally substituted, aryl groups optionally substituted;
• R3 and R4, equal to or different from each other, represent a hydrogen atom;
• or they are selected from linear or branched C1-C20 alkyl groups, cycloalkyl groups optionally substituted, aryl groups optionally substituted;
• or R2 and R4 can be optionally bound to each other so as to form, together with the other atoms to which they are bound, a saturated, unsaturated or aromatic cycle containing from 3 to 6 carbon atoms, optionally substituted with linear or branched C1-C20 alkyl groups, said cycle optionally containing other heteroatoms such as oxygen, sulfur, nitrogen, silicon, phosphorous, selenium;
• or R1 and R3 can be optionally bound to each other so as to form, together with the other atoms to which they are bound, a saturated, unsaturated or aromatic cycle containing from 3 to 6 carbon atoms, optionally substituted with linear or branched C1-C20 alkyl groups, said cycle optionally containing other heteroatoms;
• and
• X1, X2 and X3, equal to or different from each other, represent a halogen atom;
• or they are selected from linear or branched C1-C20 alkyl groups, —OCOR5 or —OR5 groups wherein R5 is selected from linear or branched C1-C20 alkyl groups.