| abstract |
A borohydride metallocene complex of a lanthanide, its process of preparation, a catalytic system incorporating a borohydride metallocene complex and a process for the copolymerization of olefins employing this catalytic system. Such a complex corresponds to one or other of the following formulae A and B: n n n n n n n n n n where, in the formula A, two ligands Cp 1 and Cp 2 , each composed of a cyclopentadienyl group, are connected to the lanthanide Ln, such as Nd, and where, in the formula B, a ligand molecule, composed of two cyclopentadienyl groups Cp 1 and Cp 2 which are connected to one another via a bridge P of formula MR 1 R 2 , where M is an element from group IVa, such as Si, and where R 1 and R 2 , which are identical or different, represent an alkyl group comprising from 1 to 20 carbon atoms, is connected to the lanthanide Ln, where L represents an alkali metal, such as Li, where N represents a molecule of a complexing solvent, such as THF, where x is an integral or non-integral number greater than 0, where p is an integer equal to or greater than 1 and where y is an integer which is equal to or greater than 0. |