Cyclic organosilicon compounds that may be employed as an electron donor for polymerization catalyst systems, polymerization catalyst systems employing the cyclic organosilicon compounds as an electron donor, methods of making the polymerization catalyst systems, and polymerization processes to produce polyolefin are disclosed. The organosilicon compounds, which are useful as electron donors in polymerization catalyst systems for the production of polyolefins, are represented by the following formula: ##STR00001## wherein Q.sub.1 and Q.sub.2 may be identical or different and are each hetero-atoms selected from the group consisting of N, O, S, Si, B, and P, with the proviso that Q.sub.1 and Q.sub.2 cannot both be N or both be O. R.sub.1 and R.sub.2 may be identical or different and are each hydrocarbon-based substituents to Q.sub.1 and Q.sub.2, respectively. The subscripts m and n are independently 0 to 3. R.sub.3 is an aliphatic, alicyclic or aromatic group. R.sub.4 is a hydrocarbon group with 1 to 6 carbon atoms. R.sub.5 is a bridging group with a backbone chain length between the two hetero-atoms Q.sub.1 and Q.sub.2 being 1-8 atoms. The bridging group is selected from the group consisting of aliphatic, alicyclic, and aromatic bivalent radicals.