Patent ID: 8071800

Claim:
A borohydride metallocene complex of a lanthanide that corresponds to formula B: where Ln represents the lanthanide having an atomic number of between 57 and 71 inclusive, where, in the formula B, a ligand composed of two identical or different fluorenyl groups Cp 1 and Cp 2 which are substituted or unsubstituted and which are connected to one another via a bridge P corresponding to the formula MR 1 R 2 , where M is an element from Group IVa of the Periodic Table of the Elements 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 chosen from the group consisting of lithium, sodium and potassium, where N represents a molecule of a complexing solvent, where x is an integral or non-integral number which is greater than 0, and where p is an integer equal to 1 or 2.