A colloidal suspension includes an organic phase and a complex of Formula I as precursor for Ziegler-Natta catalyst synthesis:
XTiCl.sub.p(OR.sup.1).sub.4−p.Math.YMg(OR.sup.2).sub.q(OR.sup.3).sub.t  (I).
In Formula I, a molar ratio of X to Y (X/Y) is from 0.2 to 5.0, p is 0 or 1, 0<q<2, 0<t<2, the sum of q and t is 2, R.sup.1, R.sup.2, and R.sup.3 are each independently a linear or branched alkyl, a linear or branched heteroalkyl, a cycloalkyl, a substituted cycloalkyl, a substituted heterocycloalkyl, a substituted aryl, or a (heteroaryl)alkyl; and R.sup.2 is not the same as R.sup.3.

A colloidal suspension includes an organic phase and a complex of Formula I as precursor for Ziegler-Natta catalyst synthesis:
XTiCl.sub.p(OR.sup.1).sub.4-p.YMg(OR.sup.2).sub.q(OR.sup.3).sub.t  (I).
In Formula I, a molar ratio of X to Y (X/Y) is from 0.2 to 5.0, p is 0 or 1, 0<q<2, 0<t<2, the sum of q and t is 2, R.sup.1, R.sup.2, and R.sup.3 are each independently a linear or branched alkyl, a linear or branched heteroalkyl, a cycloalkyl, a substituted cycloalkyl, a substituted heterocycloalkyl, a substituted aryl, or a (heteroaryl)alkyl; and R.sup.2 is not the same as R.sup.3.

A catalyst component for olefin polymerization includes magnesium, titanium, a halogen, an internal electron donor compound, and a precipitation aid. The precipitation aid includes a precipitation aid represented by general formula (I). The precipitation aid represented by general formula (I) includes isomers represented by general formula (I-a) and/or (I-b). ##STR00001##

What is disclosed is a method for preparing a catalyst system and a catalyst system for polymerizing or copolymerizing an -olefin. Catalyst component (A) is obtained by a process of reacting a magnesium complex (A-1) containing acid salts of group IB-VIIIB elements formed by contacting a magnesium halide with an acid salt solution of group IB-VIIIB metals or spherical particles adducts, an internal electron donor (A-2) of diester or diether or composite compounds, and a titanium compound (A-3). The catalyst compound (A) is contacted with a silicon compound (B) and an organoaluminium compound (C) to complete the catalyst system providing a good balance of catalyst performance in terms of activity and stereo-specificity.