Borohydride metallocene complex of a lanthanide, catalytic system including said complex, polymerization method using same and ethylene/butadiene copolymer obtained using said method
Borohydride metallocene complex of lanthanide, preparation process, catalytic system incorporating borohydride metallocene complex, process for copolymerization of olefins employing catalytic system. The complex corresponds to one or other of formulae A and B: where, in A, two ligands Cp 1 , Cp 2 , each composed of a cyclopentadienyl group, are connected to the lanthanide Ln, such as Nd, and where, in B, a ligand molecule, composed of two cyclopentadienyl groups Cp 1 , Cp 2 connected to one another via a bridge P of formula MR 1 R 2 , M is an element from group IVa, and 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, L is alkali metal, N is molecule of a complexing solvent, x is integral or non-integral number≧0, p is integer≧than 1 and y is integer≧0.
1. A borohydride metallocene complex of a lanthanide, wherein the complex corresponds to the formula B′:
where Cp 1 and Cp 2 are chosen from identical or different and substituted or unsubstituted cyclopentadienyl groups, it being possible in addition for Cp 2 to represent a substituted or unsubstituted fluorenyl group, and x is an integral or non-integral number which is greater than 0.
2. A process for the preparation of a borohydride metallocene complex of a lanthanide, comprising the reaction of a ligand salt of formula P-Cp 1 Cp 2 -L 2 and of a solution of lanthanide Ln tris(borohydride) dissolved in the complexing solvent and of formula Ln(BH 4 ) 3 N 3 , wherein the complex corresponds to the following formula B:
where Ln is a lanthanide having an atomic number of between 57 and 71 inclusive,
where, in the formula B, when y is equal to 0, two identical or different ligands Cp 1 and Cp 2 , which are each composed of a group chosen from substituted or unsubstituted cyclopentadienyl groups and substituted or unsubstituted fluorenyl groups and which are connected to one another via a bridge P corresponding to the formula MR 1 R 2 , where M is silicon and where R 1 and R 2 , which are identical or different, represent an alkyl group comprising from 1 to 20 carbon atoms, are connected to the lanthanide Ln,
where L represents an alkali metal chosen from the group consisting of lithium, sodium and potassium,
where N represents a molecule of a complexing solvent, such as an ether,
where x is an integral or non-integral number which is greater than 0,
where y is an integer which is equal to or greater than 0, and
where p is an integer which is equal to 1 or 2.