Redox-fluid ligand stabilised as triradical for the first time

An exotic triradical aluminium complex is the first of its kind to be isolated and characterised. Containing three ‘redox non-innocent’ dithiolene ligands stabilised in radical form, the new species exists in an unusual quartet ground state and could have implications for the design of superconducting and single-molecule magnetic materials.

1,2-dithiolene complexes have attracted widespread interest over the last 60 years thanks to their versatile optical, magnetic and conductive properties. The ligand itself can alter its oxidation state between dianion, radical monoanion and neutral forms, facilitating easy redox changes with the metal centre. This motif is particularly prevalent in metalloenzymes but the variable spin states and flexible redox properties also make these complexes of interest in quantum computing as molecular qubits and in the development of superconducting materials. However, while many different metal dithiolene complexes have been studied, examples of the ligand in radical form are scarce as the metal centre favours interactions with the dianionic form.