Phenolates represent versatile ligand scaffolds capable of stabilizing a large variety of both oxophilic metal centers and late transition elements. Over the past 50 years, they have played a prominent role in the rise of discrete metal complexes employed to promote, initiate and/or catalyze a variety of controlled homogeneous polymerization reactions. This chapter features a selection of the most remarkable metal phenolate complexes used in the polymerization of olefins, styrene and dienes, cyclic esters and (meth)acrylates. Coordination-insertion polymerization reactions are emphasized, but other types of mechanisms are also treated. Specifically highlighted are catalytic systems where the phenolate ligands have proved valuable ancillaries, to provide either exceptional stability to active species and to generate highly productive catalysts, and/or to control the polymerization reactions, imparting a unique capacity to obtain polymers with tailored macromolecular features: molecular weights and their dispersion, (co)monomer distribution and regio/stereoselectivity.
