Catalysts useful for polymerizing olefins are disclosed. The catalysts comprise a transition metal complex, an optional activator, and an optional support. The complex is the reaction product of a Group 3-6 transition metal source, an optional alkylating agent, and a ligand precursor comprising a 2-imino-8-anilinoquinoline or a 2-aminoalkyl-8-anilinoquinoline. The catalysts, which are easy to synthesize by in-situ metallation of the ligand precursor, offer polyolefin manufacturers good activity and the ability to make high-molecular-weight ethylene copolymers that have little or no long-chain branching.