Synthesis and characterization of C-1- and C-2-bridged bis(fluorenyl) complexes of zirconium and hafnium and their application in catalytic olefin polymerization

The addition of n-butyl lithium to bis-biphenylene propene (1) or 1,4-bis-biphenylene butadiene (2) followed by the reaction with zirconium tetrachloride or hafnium tetrachloride leads to C-1- or C-2-bridged bis(fluorenyl) complexes of zirconium or hafnium containing substituents in the bridge. Complexes of the type (C13H8-C(H)Bu-C13H8)MCl2, (M = Zr (3), Hf (4)) are the first known examples of C-1-bridged bis(fluorenyl) complexes of a group 4 metal.