Conferencia: "Isolation of novel compounds through matrix isolation photochemistry followed by FTIR spectroscopy"

ROSANA M. ROMANO

Buenos Aires

Workshop; International Workshop on Infrared Spectroscopy Applied to Biological and Biomimetic Systems:From the Isolated Molecule to the Cell; 2007

Matrix isolation fotochemistry followed by FTIR analysis, in combination with theoretical calculations, is a powerful technique for the isolation of novel species, the determination of conformational equilibrium, the elucidation of photochemical reaction mechanisms through the detection of reactive intermediates, and the study of intermolecular interactions or molecular complexes. Results obtained during the last few years using this technique will be presented. For instance, the isolation of BrC(O)SCl was possible, either by the photochemical evolution of ClC(O)SBr or by the photochemical reaction between OCS and BrCl. Other members of the sulfenyl carbonyl family of compounds were prepared  by matrix reactions induced by UV-visible irradiation, such as BrC(O)SBr and IC(O)SBr. The very well know “phosgene” family was completed by the isolation of the last two members O=CICl and O=CIBr using the same strategy. The studies were extended to ClC(S)SCl, ClC(S)SBr, BrC(S)SCl and BrC(S)SBr. We also have reported the first detection of CH3SF in its normal and perdeuterated form, by photolysis of matrix isolated FC(O)SCH3 (or FC(O)SCD3). More recently, compounds of the XC(O)SeX family were isolated by the photochemical reaction between OCSe and X2 molecules. Not only the isolation of novel species but also the study of conformational equilibria, reaction mechanisms, the detection of reactive intermediates like free radicals and molecular complexes, are the main objectives of our work. The photochemical induced matrix reaction between OCSe and F2 constitutes an example. In this reaction both, syn- and anti-FC(O)SeF, were isolated. The van der Waals complex O=C=Se···F–F has been shown to play an important role in the formation of the photoproducts. The anti-FC(O)SeF is formed in the first place, and then transformed, through a randomization process, into syn-FC(O)SeF. The important role the theoretical calculations play in the interpretation of the experimental results will be discussed.