Bicyclic organosilicon compounds as electron donors for polyolefin catalysts

A composition comprising a compound of the formula:

• wherein Q1, Q2, Q3, and Q4 are each a hetero-atom independently selected from the group consisting of N, O, S, Si, B, P;
• wherein R1, R2, R3, and R4 are independently each a hydrocarbon-based substituent to Q1, Q2, Q3, and Q4, respectively;
• wherein i, j, m, and n are independently 0-3;
• and
• wherein R5 and R6 are independently each a bridging group with backbone chain length between their two respective hetero-atoms Q1 and Q3, and Q2 and Q4, respectively, being 1-8 atoms,
• wherein the backbone of said bridging group is selected from the group consisting of aliphatic, alicyclic, and aromatic radicals,
• wherein one or more of the carbon atoms and hydrogen atoms of R1, R2, R3, R4, R5, or R6 is replaced with a hetero-atom selected from the group consisting of N, O, S, Si, B, P, and halogen atoms.

A composition comprising a compound of the formula:

• wherein Q1, Q2, Q3, and Q4 are each a hetero-atom independently selected from the group consisting of N, O, S, Si, B, P;
• wherein R1, R2, R3, and R4 are independently each a hydrocarbon-based substituent to Q1, Q2, Q3, and Q4, respectively;
• wherein i, j, m, and n are independently 0-3;
• and
• wherein R5 and R6 are independently each a bridging group with backbone chain length between their two respective hetero-atoms Q1 and Q3, and Q2 and Q4, respectively, being 1-8 atoms,
• wherein the backbone of said bridging group is selected from the group consisting of aliphatic, alicyclic, and aromatic radicals,
• wherein two or more of said R1, R2, R3, R4, R5, and R6 are linked to form a saturated or unsaturated monocyclic or polycyclic ring.

A method for polymerizing an alpha-olefin comprising polymerizing alpha-olefin in the presence of 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 Q1, Q2, Q3 and Q4 are each a hetero-atom independently selected from the group consisting of N, O, S, Si, B, P;
• wherein R1, R2, R3 and R4 are independently each a hydrocarbon-based substituent to Q1, Q2, Q3 and Q4, respectively;
• wherein i, j, m, and n are independently 0-3;
• and
• wherein R5 and R6 are independently each a bridging group with backbone chain length between their two respective hetero-atoms Q1 and Q3, and Q2 and Q4, respectively, being 1-8 atoms,
• wherein the backbone of said bridging group is selected from the group consisting of aliphatic, alicyclic and aromatic radicals.