Trapping of radicals in the coordination spheres of metals

The use of hexamethylphosphoramide (HMPA) or other sterically demanding groups as stabilizing ligands allows the successful isolation of a series of structurally characterizable complexes of ketyl radicals with alkali, alkaline earth, and lanthanide metal. It has been demonstrated that the stability and reactivity of the ketyl radicals strongly depend on both the nature of the metals to which they are bound and the steric and electronic properties of the ancillary ligands, as well as the structure of their parent ketones.