Preparation of the novel XC(O)SeX species (X = Cl, Br) through matrix photochemical reactions of OCSe with Cl2 and Br2 at cryogenic temperatures

The photochemical reactions between OCSe and Cl-2 or Br-2 isolated in solid argon at cryogenic temperatures were studied by means of FTIR spectroscopy. The OCSe center dot center dot center dot Cl-2, OCSe center dot center dot center dot Br-2 and SeCO center dot center dot center dot Br-2 molecular complexes were identified by the shifts of the OCSe IR absorptions on complexation, and also by the IR activation of the Cl-Cl vibration in the first adduct. The hitherto unknown ClC(O)SeCl and BrC(O)SeBr molecules were formed upon UV - Vis irradiation of the matrix. The former was firstly obtained in the anti form, and subsequently photochemically transformed into the thermodynamically more stable syn conformation, while only the syn rotamer of BrC(O)SeBr was produced. The characterization of the novel species through their IR spectra was supported by the comparison with results of quantum chemical calculations. (c) 2007 Elsevier B.V. All rights reserved.