Switchable Molecules: A Radical Approach

The majority of the ligands used in metal complexes are not 'redox-active', that is, any redox processes in such materials are dominated by the metal centre. A more interesting route involves so called 'redox-active' ligands which undergo redox processes before the metal centre. When used in tandem with a suitable choice of metal they have the potential to facilitate multielectron transformations and are obvious candidates to replace the catalytic processes commonly found in expensive and scarce noble metals like platinum or irridum. This is typified by aerobic alcohol oxidation catalysts such as those reported by Stahl et al. which are chemoselective and high yielding. Metal complexes containing 'redox active' ligands have also been utilised to great effect in molecular magnetism, biomimetic studies of redox-active metalloenzymes, quantum computing, and molecular spintronics. 

Our initial foray into radical inorganic chemistry involved a nitroxide based 'redox-active' ligand and was a study of the interplay between radical–metal exchange and spin-crossover properties of a small series of iron and cobalt metal radical complexes. This revealed small redox active molecules which could undergo significant physical and electronic changes offering a unique switchable system. Such advanced materials will be explored to probe their fundamental and applied properties.