Isolation of the Triplet Ground State Aminyl Diradical

Spin cycle: A high-spin nitrogen-centered (aminyl) diradical with a triplet (S=1) ground state (see picture) has a large singlet-triplet energy gap (ΔEST). Effective shielding of the reactive aminyl radical centers provides stability at room temperature and maintains the planarity of the π system required for the triplet ground state and large ΔEST value. The diradical assembles in solution to form a π-dimer-like structure with weak exchange coupling.