Organometallic transition metal compound, biscyclopentadienyl ligand system, catalyst system and preparation of polyolefins

摘要

Organometallic transition metal compounds of the formula (I) where M¹ is an element of group 3, 4, 5 or 6 of the Periodic Table of the Elements or the lanthanides; X are identical or different and are each halogen, hydrogen, C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₂-aryl, alkylaryl or arylalkyl having from 1 to 10 carbon atoms in the alkyl part and from 6 to 22 carbon atoms in the aryl part, -OR⁵ or -NR⁵R⁶, where two radicals X may also be joined to one another or two radicals X may together form a substituted or unsubstituted diene ligand, in particular a 1,3-diene ligand; where R⁵ and R⁶ are each C₁-C₁₀-alkyl, C₆-C₁₅-aryl, alkylaryl, arylalkyl, fluoroalkyl or fluoroaryl each having from 1 to 10 carbon atoms in the alkyl radical and from 6 to 22 carbon atoms in the aryl radical; n is a natural number from 1 to 4 which is equal to the oxidation number of M¹ minus 2; R¹ is a C₂-C₄₀ radical which is branched in the alpha position; R² is hydrogen or a C₁-C₄₀ radical which may be branched or unbranched in the alpha position; R³, R^3a and R^3b are identical or different and are each hydrogen or a C₁-C₄₀ radical, where at least one of the radicals R³, R^3a, R^3b is not hydrogen; R⁴ is a substituted or unsubstituted C₆-C₄₀-aryl radical or C₂-C₄₀-heteroaromatic radical containing at least one heteroatom selected from the group consisting of O, N, S and P; T is a divalent C₁-C₄₀ group which together with the cyclopentadienyl ring forms a further saturated or unsaturated ring system having a ring size of from 5 to 12 atoms, where T may contain the heteroatoms Si, Ge, N, P, O or S withing the ring system fused onto the cyclopentadienyl ring; and Z is a bridge consisting of a divalent atom or a divalent group, can be used in catalyst systems for preparing polyolefins by polymerization or copolymerization of at least one olefin. Biscyclopentadienyl ligand systems which have such a substitution pattern and can be used for preparing these organometallic transition metal compounds are also provided