Amine Tris(phenolate) Ligands as a Versatile Scaffold for Early and Late Transition Metals: Synthesis and Application

Amine tris-(phenolate) (usually abbreviated as tpa) ligands have drawn much interest as ligands for early transition metals, because they create stable complexes with broad catalytic applications in oxygen transfer reactions, polymerization, and other organic/organometallic fields of chemistry. Over the last 10 years, attention has been given to synthesizing tpa ligands with steric and electronic modifications, enabling fine-tuning of selectivity and reactivity in early and late transition metal complexes. Despite initial studies predominantly focusing on early transition metal complexes with tpa ligands in a broad sense, the field has expanded to late transition metals, uncovering new opportunities in catalysis, chirality transfer, polymerization, and oxygen transfer reactions. This review emphasizes early transition metals with tpa ligands and highlights their synthesis, application, and recent advancements after 2020 to the present, while also exploring the emerging development of late transition metal complexes and their applications in catalysis and synthetic reactions.