Process for the preparation of metallocene complexes

A process to prepare a bridged bis(indenyl) ligand comprising reacting a 2-indenylboranic acid or ester of formula (1)

• wherein R7 and R8 each independently stand for H, an alkyl of 1 to 6 C-atoms or wherein R7 and R8 form a ring together with the O atoms to which they are bound,
• wherein R1, R2, R3, R4, R5, and R6 each independently stand for H, a hydrocarbon radical having 1-20 C-atoms, a halide, an alkoxy group having 1-6 C-atoms, an alkylsulfide, an amine, a Si or B containing group or a P-containing group with a bromosubstituted compound of formula (2)
• (Br)2—R (2)
• wherein R stands for a bridging group containing at least two sp2-hybridised carbon atoms that are bonded to the indenyl groups at the 2-positions in a solvent in the presence of bis(triphenylphosphine)palladium dichloride and a base to form the corresponding bridged bis(indenyl) ligand of formula (3)
• wherein R and R1, R2, R3, R4, R5 are R6 as described above.