Thermal hysteresis in dithiadiazolyl and dithiazolyl radicals induced by supercooling of paramagnetic liquids close to room temperature: a study of F3CCNSSN and an interpretation of the behaviour of F3CCSNSCCF3

Abstract

The trifluoromethyl-substituted dithiadiazolyl and dithiazolyl radicals, F₃CCNSSN (1) and F₃CCSNSCCF₃ (2) associate through π*–π* covalent and electrostatic S^δ+…N^δ− interactions in the solid state, but melt with a dramatic volume increase to generate paramagnetic liquids; these radicals exhibit thermal hysteresis, which arises through a meta-stable super-cooled liquid state, close to room temperature.