| abstract |
The invention relates to a borohydride metallocene complex of a lanthanide, the preparation method thereof, a catalytic system including said borohydride metallocene complex, a method for the copolymerisation of olefins using said catalytic system and an ethylene/butadiene copolymer obtained using said method, having butadiene units with 1,2-cyclohexane or 1,2 and 1,4-cyclohexane chains. The inventive complex has one of the following formulas (A and B), wherein, in formula A, two molecules of ligands Cp1 and Cp2 are linked to the lanthanide Ln, such as Nd, said ligand molecules each consisting of a fluorenyl group, and, in formula B, a ligand molecule is linked to the lanthanide Ln, said ligand molecule consisting of two fluorenyl groups Cp1 and Cp2 which are interlinked by means of a bridge P having formula MR1R2, in which M is an element from column IVA, such as Si, and R1 and R2, which may be identical or different, represent an alkyl group having between 1 and 20 carbon atoms. According to the invention, L represents an alkali metal, such as Li, N represents a molecule of a complexing solvent, such as THF, x is an integer or a non-integer which is greater than 0 and p is an integer which is equal to or greater than 1. |