Transition‐Metal Complexes Containing the Dinucleating Tetra‐ N ‐Dentate 3,5‐Bis(2‐pyridyl)pyrazole (Hbpp) Ligand – A Robust Scaffold for Multiple Applications Including the Catalytic Oxidation of Water to Molecular Oxygen

A large diversity of transition-metal complexes bearing the dinucleating tetra-N-dentate ligand 3,5-bis(2-pyridyl)pyrazole (Hbpp) is described. Hbpp is a compartamental ligand and can allow the formation of both mononuclear and dinuclear complexes bridged by the pyrazolate unit of the Hbpp. Furthermore, a slightly related ligand even allows the preparation of tetranuclear complexes. This large family of complexes has been shown to have multiple applications in diverse areas of science, from basic coordination properties to catalysis. From the former perspective phenomena such as linkage isomerization, intrasupramolecular interactions, and exciting magnetic properties have been described. In the field of catalyis it has been shown that this family of complexes is active in a range of reactions, including alcohol oxidation, epoxidation, hydrogen transfer, and water oxidation.