Thermal hysteresis in dithiadiazolyl and dithiazolyl radicals induced by supercooling of paramagnetic liquids close to room temperature: a study of F3CC???NSSN??? and an interpretation of the behaviour of F3CC???SNSC???CF3Electronic supplementary information (ESI) available: Synthesis of 1; packing diagrams of 1 and 2; ab initio calculations on the association modes of 1 and 2; estimates of the energy of association of 2 based on a simple electrostatic model; molecular electrostatic potential maps of 1 and 2 and a comparison of the charge distribution in 1 and 2 from semi-empirical and ab initio calculations; curve-fits of the magnetic data of 1 utilising a Curie???Weiss, exchange-coupled dimer and monomer???dimer equilibrium models for the