Photochemical gas-phase reactions between Cl2, SO2 and O2: Preparation of the novel peroxide ClSO2OOSO2Cl

ROSANA M. ROMANO; CARLOS O. DELLA VÉDOVA; HELMUT BECKERS; HELGE WILLNER

INORGANIC CHEMISTRY

Año: 2009 vol. 48 p. 1906 - 1910

0020-1669

Photochemically induced gas-phase reactions of Cl2/SO2/O2 mixtures at -78 °C have been investigated on a preparative scale. The sulfuryl chlorides ClSO2(OSO2)nCl, n ) 0, 1, or 2, along with SO3 and the hitherto unknown bis(chlorosulfuryl)peroxide, ClSO2OOSO2Cl, have been obtained. The new peroxide has been purified by trap-totrap distillation and conclusively characterized by gas-phase and matrix IR, as well as Raman, spectroscopy. At room temperature, the peroxide decomposes to form quantitatively Cl2 and SO3. DFT calculations suggest that ClSO2OOSO2Cl occurs at ambient temperatures in at least two different rotamers, whereas in matrix-isolation experiments in Ar at 15 K only the most stable form has been found. The mechanism of the formation of the peroxide via the ClSO2OO• peroxy radical and the supposed involvement of the ClSO3• intermediate is discussed.