Methods and apparatus to form a catalyst precursor, comprising combining in a reactor magnesium, an alkoxysilane compound, a halogenized silicon compound, a halogenized transition metal compound, a substituted aromatic furan compound having a structural formula, ##STR00001## and an alkyl halide or aromatic halide compound to obtain a solid catalyst precursor, wherein the alkoxysilane compound and halogenized silicon compound are combined prior to either being exposed to the halogenized transition metal compound, and wherein the alkyl halide or aromatic halide compound is introduced to the reactor as the final step.