| abstract |
A method of halogenating a precursor to form a polymerization procatalyst is disclosed whereby a magnesium/transition metal-containing alkoxide complex precursor is contacted with a halogenating agent selected from alkylaluminum halide, TiX 4 , SiX 4 , BX 3 , and Br 2 , where halide and X are reach respectively a halogen, and when an alkylaluminum halide, TiX 4 , SiX 4 , BX 3 , and Br 2 are used as the halogenating agent, they are used together or in combination in a multi-step halogenation. The procatalyst then can be converted to an olefin polymerization catalyst by contacting it with a cocatalyst and optionally a selectivity control agent, and used to polymerize olefins in high yield with desired properties. |