Molecular tailoring of spin-transition materials: preparation, crystal structure and magnetism of trifluoromethyl-pyridyl-1,3,2-dithiazolyl

The alpha-phase of pyridyl-1,3,2-dithiazolyl, pyDTA, has previously been shown to exhibit a distorted pi-stacked structure which is diamagnetic at low temperature. Unlike other pi-stacked dithiazolyl radicals it does not undergo a first order phase transition to a regular pi-stacked paramagnetic phase even upon warming to its melting point. Here we show that incorporation of a trifluoromethyl group destabilises the diamagnetic pi*-pi* dimer and the title compound (1) exhibits a spin-transition (without hysteresis) at 50 K.