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Effects of hyperconjugation on the electronic structure and photoreactivity of organic sulfonyl chlorides.

TitleEffects of hyperconjugation on the electronic structure and photoreactivity of organic sulfonyl chlorides.
Publication TypeJournal Article
Year of Publication2009
AuthorsMartin-Diaconescu, V, Kennepohl, P
JournalInorg. Chem.
Volume48
Pagination1038–44
Date Publishedfeb
ISSN1520-510X
KeywordsDFT, ELECTRONS, models, MOLECULAR, molecular structure, Organic Chemicals, Organic Chemicals: chemistry, PHOTOCHEMISTRY, Spectrum Analysis, Sulfinic Acids, Sulfinic Acids: chemistry, sulfur redox, XAS
Abstract

The electronic structure of organic sulfonyl compounds of the form RSO(2)G (G = -Cl, -OH, -CH(3)) is investigated to evaluate the effect of aryl R groups on photocleavage of the S-G bond. Sulfur K-edge X-ray absorption spectroscopy (XAS) provides a direct measure of the empty low-lying molecular orbitals in these complexes and, in combination with DFT calculations, a detailed description of the bonding in these compounds. The presence of an aryl group bound to the sulfonyl moiety has a significant impact on the spectroscopy and electronic structure of the site. The analysis suggests that the SCl(sigma*) orbital is significantly affected by mixing with the aryl pi* manifold. This mixing is dependent upon the nature of G and is most pronounced in the sulfonyl chlorides, where the energy of the SCl(sigma*) orbital is lowered by approximately 0.5 eV. The observed mixing is best described as excited-state hyperconjugation of the aryl pi system into the SCl(sigma*) orbital. The magnitude of the effect can be estimated directly from the S K-edge XAS spectra. These results are discussed in relation to the observed photochemistry of RSO(2)Cl, which is significantly enhanced when R = aryl as compared to alkyl substituents.

URLhttp://pubs.acs.org/doi/abs/10.1021/ic50073a047 http://www.ncbi.nlm.nih.gov/pubmed/19132932
DOI10.1021/ic801665f