A Chemistry of Ruthenium-Tris(2-pyridylmethyl)amine Complexes

Abstract

This account describes a current summary of our research on ruthenium complexes having tris(2-pyridylmethyl)amine (TPA) and its derivatives as ligands. Topics include their characteristics, catalytic oxygenations of organic compounds including alkanes, alkenes, and alcohols by peroxide activation and proton-coupled electron transfer to generate Ru(IV)=O complexes as reactive species, Ru-TPA complexes with redox-active heteroaromatic coenzymes such as pterins and flavin analogues to elucidate their characteristics, construction of specific coordination spheres by introducing functional moieties to the TPA ligand via amide linkage to develop non-covalent interactions in the first and second coordination spheres, and bistability in photochromic structural change. The important features of the Ru-TPA complexes are following: (1) Reliable stability due to the π-back bonding from 4d_π orbitals of the ruthenium center to π* orbitals of heteroaromatic ligands, (2) Very clear reversible redox behaviour, (3) Availability of a wide range of oxidation states and a variety of reactivity at the ruthenium center, (4) Feasibility of derivatization of TPA toward the construction of unique coordination environments, and (5) Accessibility to bistability in photochemical and thermal processes.