Phosphine phosphonate and phenoxyphosphine ligands bearing polyethylene glycol (PEG) chains are used as described herein to produce heterobimetallic catalysts. The ligands can be metallated selectively with palladium or nickel and secondary metal ions to provide well-defined heterobimetallic compounds. These heterobimetallic complexes exhibit accelerated reaction rates and greater thermal stability in olefin polymerization compared to other catalysts.