Pyridine complex of zirconium, catalytic system comprising said pyridine complex of zirconium and process of (co)polymerization of conjugated dienes

Pyridine complex of zirconium having general formula (I):

• in which:
• R1 and R2, identical or different, represent a hydrogen atom;
• or are selected from linear or branched, optionally halogenated C1-C20, alkyl groups, optionally substituted cycloalkyl groups, or optionally substituted aryl groups;
• R3, R4, R5 and R6, identical or different, represent a hydrogen atom;
• or are selected from linear or branched, optionally halogenated C1-C20, alkyl groups, optionally substituted cycloalkyl groups, optionally substituted aryl groups, nitro groups, hydroxyl groups, or amino groups;
• X1, X2 and X3, identical or different, represent a halogen atom;
• or are selected from linear or branched C1-C20, alkyl groups, —OCOR7 groups or —OR7 groups in which R7 is selected from linear or branched C1-C20, alkyl groups;
• or one of X1, X2 and X3 represents a group having general formula (II):
• in which R1, R2, R3, R4, R5 and R6, have the same meanings described above.