Condensation of CF3C(=NH)NH2 With SCl2 yielded the dithiadiazolylium salt, [CF3CNSSN]Cl which could be reduced to[CF3CNSSN](2) with Zn/Cu couple in SO2. [CF3CNSSN](2) is a diamagnetic dimer in the solid state but melts at 308 K to give a paramagnetic liquid. On cooling the radical enters a metastable state before immediately resolidifying below 295 K The thermal hysteresis was probed by EPR spectroscopy. Metastable samples spontaneously solidified after an induction period, typically between ca. 5 and 30 min, consistent with the variable time necessary to form a seed crystal from which crystallization can occur
The preparation and isolation of 5-methyl-1,3,2,4-dithiadiazolyl and the facile rearrangement of the 1,3,2,4-dithiadiazolyl radicals to the disulphide isomers, 2,3,1,4-dithiadiazolyl
作者:Neil Burford、Jack Passmore、Melbourne J. Schriver
DOI:10.1039/c39860000140
日期:——
The radical5-methyl-1,3,2,4-dithiadiazolyl has been prepared and isolated, and it and two new derivatives undergo essentially quantitative isomerisation to 2,3,1,4-dithiadiazolyl at room temperature; the rate of isomerisation follows second order kinetics and the mechanism is postulated to involve an unstable π*–π* dimer intermediate.
Electron spin resonance spectroscopy of free radicals
作者:Shirley A. Fairhurst、Leslie H. Sutcliffe、Keith F. Preston、Arthur J. Banister、Andrew S. Partington、Jeremy M. Rawson、Jack Passmore、Melbourne J. Schriver
DOI:10.1002/mrc.1260311114
日期:1993.11
powder ESR spectra of the 4‐trifluoromethyl‐1,2,3,5‐dithiadiazolyl and 4‐pentafluorophenyl‐1,2,3,5‐dithiadiazolyl freeradicals were analysed. Comparison of the ESR parameters with those obtained for the protonated equivalents shows that fluorination produces a drift of unpaired electronspin density away from the nitrogen 2px orbitals towards sulphur 3px orbitals (x is the direction perpendicular to the
Thermal hysteresis in dithiadiazolyl and dithiazolyl radicals induced by supercooling of paramagnetic liquids close to room temperature: a study of F<sub>3</sub>CCNSSN and an interpretation of the behaviour of F<sub>3</sub>CCSNSCCF<sub>3</sub>
作者:Hongbin Du、Robert C. Haddon、Ingo Krossing、Jack Passmore、Jeremy M. Rawson、Melbourne J. Schriver
DOI:10.1039/b202627a
日期:——
The trifluoromethyl-substituted dithiadiazolyl and dithiazolyl radicals, F3CCNSSN (1) and F3CCSNSCCF3 (2) associate through π*–π* covalent and electrostatic Sδ+…Nδ− 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.