The trifluoromethyl-substituted dithiadiazolyl and dithiazolyl radicals, F3CCNSSN (I) and F3CCSNSCCF3 (II) assoc. through p*-p* covalent and electrostatic Sd+...Nd- interactions in the solid state, but melt with a dramatic vol. increase to generate paramagnetic liqs.; these radicals exhibit thermal hysteresis, which arises through a meta-stable super-cooled liq. state, close to room temp. [on SciFinder (R)]