Olefin polymerization catalyst precursors are described herein. The precursors are generally characterized by the formula: ##STR1##

wherein M is a transition metal selected from groups 8 to 10 of the Periodic Table; n is an integer of from 1 to 3; Q is a halogen or a C₁ to C₂ alkyl group; PY is a pyridinyl group, which is coordinated with M through the nitrogen atom of said pyridinyl group; R is a C₁ to C₂₀ hydrocarbyl group; R" is a C₁ to C₂₀ hydrocarbyl group; A₁ is a monoaromatic group, which is substituted or unsubstituted; and A₂ includes multiple aromatic groups, which are substituted or unsubstituted.