SULFUR-COMPOUNDS .164. THERMAL POLYMERIZATION OF THE CYCLIC SELENIUMSULFIDE 1,2-SE2S5 STUDIED BY DSC, HPLC, RAMAN-SPECTROSCOPY, AND X-RAY-DIFFRACTION

Solid 1, 2-Se2S5 polymerizes endothermically at 47-degrees-C to give a linear polymer which after stretching and extraction consists of heli cal molecules similar to those of polymeric sulfur. Heating of the pol ymer results in slow exothermic depolymerization at 84-degrees-C to gi ve a mixture of seven cyclic SenS8-n molecules which melts at 111-degr ees-C. When the polymeric Se2S5 is refluxed with CS2 the initial depol ymerization products are 1, 2-Se2S5, SeS5 and 1,2,3-Se3S5 but in addit ion SeS7 and 1,2-Se2S6 are formed. These results indicate the atomic s equence -Se-S5-Se- in the polymer. The powder x-ray diffraction patter n and Raman spectrum of the polymer as well as its lattice parameters are reported and the probable mechanism of its depolymerization is dis cussed.