Patent ID: 7790819

Claim:
A catalyst system for the polymerization or co-polymerization of alpha-olefin comprising a solid Ziegler-Natta type catalyst component, a co-catalyst component, and an electron donor component comprising at least one cyclic organosilicon compound of the formula: wherein Q 1 , Q 2 , Q 3 and Q 4 are each a hetero-atom independently selected from the group consisting of N, O, S, Si, B, P; wherein R 1 , R 2 , R 3 and R 4 are independently each a hydrocarbon-based substituent to Q 1 , Q 2, Q 3 and Q 4 , respectively; wherein i, j, m, and n are independently 0-3; and wherein R 5 and R 6 are independently each a bridging group with backbone chain length between their two respective hetero-atoms Q 1 and Q 3 , and Q 2 and Q 4 , respectively, being 1-8 atoms, wherein the backbone of said bridging group is selected from the group consisting of aliphatic, alicyclic and aromatic radicals.