The pentafluoroorthotellurate group (teflate, OTeF5) is a monodentate O-donor ligand system with a low tendency to bridge metal centers and similar electron-withdrawing properties to those of fluoride. This combination of properties has enabled the formation of the compounds [Mn(OTeF5)4]2− and [Mn(OTeF5)5]2−, which showcase unprecedented homoleptic environments of monodentate O-donor ligands in mononuclear manganese complexes in medium oxidation states, which would be analogues of the well-studied low-valent fluoromanganates.
You can read here more about our new paper, which has been just accepted in Chemical Science.