Structure and magnetic properties of a sulfur–nitrogen radical, methylbenzodithiazolyl

An X-ray crystal structure of the methylbenzodithiazolyl radical MeC6H3S2N˙, MBDTA, reveals that it forms a regularly spaced π-stack motif in the solid state; variable temperature magnetic studies show that the susceptibility passes through a broad maximum at 140 K indicative of exceptionally strong antiferromagnetic coupling for an organic radical possessing extended magnetic interactions. Its behaviour can be modelled as a two-dimensional Heisenberg square lattice of S = 1/2 ions with J = −72 K.