| abstract |
Provided is a catalyst for the polymerisation of olefins of general formula: n R″(C 4 R′ m C 5 C 4 R′ n )XMeQ n wherein X is an hetero-atom ligand with one or two lone pair electrons selected from the elements of Group VA or VIA which can be substituted or non-substituted: (C 4 R m ′C 5 C 4 R n ′) is a symmetrically substituted, 3,6-substituted fluorenyl; R′ is hydrogen or hydrocarbyl radical having from 1-20 carbon atoms, a halogen, an alkoxy, an alkoxy alkyl or an alkylamino or alkylsilylo radical, each R′ may be the same or different and m and n independently are 1, 2 3 or 4, with the proviso that the bilateral symmetry is maintained; R″ is a structural bridge between X and the (C 4 R′ m C 5 C 4 R′ n ) ring to impart stereorigidity; Q is a hydrocarbyl radical having 1-20 carbon atoms or is a halogen; Me is a Group IIB, IVB, VB, or VIB metal as positioned in the Periodic Table of Elements; and Me can be in any of its theoretically possible oxidation states. n Also provided are olefin monomers (particularly propylene) polymerised using these catalysts to form syndiotactic/atactic block polymers of high molecular weight and comprising at least 70% of syndiotactic triads. |