The atmospherically relevant reactions between dimethyl selenide(DMSe) and the molecular halogens (X2 = Cl2, Br2, and I2) have been studied withab initio calculations at the MP2/aug-cc-pVDZ level of theory. Geometryoptimization calculations showed that the reactions proceed from the reagents tothe products (CH3SeCH2X + HX) via three minima, a van der Waals adduct(DMSe:X2), a covalently bound intermediate (DMSeX2), and a product-likecomplex (CH3SeCH2X:HX). The computed potential energy surfaces are used topredict what molecular species are likely to be observed in spectroscopicexperiments such as gas-phase photoelectron spectroscopy and infrared matrixisolation spectroscopy. It is concluded that, for the reactions of DMSe with Cl2and Br2, the covalent intermediate should be seen in spectroscopic experiments,whereas, in the DMSe + I2 reaction, the van der Waals adduct DMSe:I2 should beobserved. Comparison is made with previous related calculations and experimentson dimethyl sulfide (DMS) with molecular halogens. The relevance of the resultsto atmospheric chemistry is discussed. The DMSeX2 and DMSe:X2 intermediates are likely to be reservoirs of molecular halogens in the atmosphere which will lead on photolysis to ozone depletion.
|Numero di pagine||9|
|Rivista||JOURNAL OF PHYSICAL CHEMISTRY. A, MOLECULES, SPECTROSCOPY, KINETICS, ENVIRONMENT, & GENERAL THEORY|
|Stato di pubblicazione||Published - 2012|
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