Ligands, compositions, and metal-ligand complexes that incorporate phenol-heterocyclic compounds are disclosed that are useful in the catalysis of transformations such as the polymerization of monomers into polymers. The catalysts have high performance characteristics, including high comonomer incorporation into ethylene/olefin copolymers, where such olefins are for example, 1-octene, propylene or styrene. The catalysts particularly polymerize styrene to form polystyrene.