ORGANOMETALLIC TRANSITION METAL COMPOUND, BISCYCLOPENTADIENYL LIGAND SYSTEM, CATALYST SYSTEM AND PROCESS FOR PREPARING POLYOLEFINS

An organometallic transition metal compound (I) is new. An organometallic transition metal compound of formula (I) is new: [Image] M 1>metal of group 3-6 of periodic table or lanthanides; X : organic or inorganic radical, in which two radicals optionally joined together; n : 1-4; T 1>, T 2>divalent group chosen from -O-, -S-, -Se-, -Te-, -N(R 1>3>)-, P(R 1>3>)-, -As(R 1>3>)-, -Sb(R 1>3>)-, Si(R 1>3>) 2-, -C(R 1>3>R 1>4>)-C(R 1>3>R 1>5>)- or -C(R 1>4>)=C(R 1>5>)-; R 1>-R 3>, R 7>-R 9>, R 1>3>-R 1>5>hydrogen or 1-40C organic radical, R 3>is not methyl when T 1>is -C(H)=C(H)-; R 4>-R 6>, R 1>0>-R 1>2>hydrogen, halogen or 1-40C organic radical, or two adjacent radicals R 4>-R 6>, R 1>0>-R 1>2>together with atoms form monocyclic, polycyclic, 1-40C (un)substituted ring system containing hetero atoms chosen from O, S, Se, Te, N, P, As, Si and Sb; and A : bridge having divalent atom or divalent group. When T 1>or T 2>is -O-, -S-, -Se- or -Te-, R 3>together with R 4>and/or radical R 9>together with R 1>0>forms monocyclic or polycyclic, 1-40C (un)substituted ring system containing hetero atoms chosen from O, S, Se, Te, N, P, As, Sb and Si. Independent claims are also included for: (1) biscyclopentadienyl ligand system of formula (II) or its double bond isomers; (2) catalyst system for polymerization of olefins, which comprises at least one organometallic transition metal compound and at least one co-catalyst which converts organometallic transition metal compound into a species having polymerization activity with respect to at least one olefin; (3) process for preparation polyolefin by polymerization or copolymerization of at least one olefin in presence of the catalyst system; (4) use of biscyclopentadienyl ligand system for preparing the organometallic transition metal compound; (5) process for preparation of organometallic transition metal compound, which involves reacting biscyclopentadienyl ligand system or bisanion with a transition metal compound; and (6) polyolefin obtained by the above method. [Image] R 1>-R 1>2>,T 1>,T 2>,A : as defined above;.