Conformational space of the Pseudosaccharin allyl ether 3-(allyloxy)-1,2-benzisothiazole 1,1-dioxide in gas phase and in rare gas matrices. | - CCMAR -

Journal Article

TitleConformational space of the Pseudosaccharin allyl ether 3-(allyloxy)-1,2-benzisothiazole 1,1-dioxide in gas phase and in rare gas matrices.
Publication TypeJournal Article
AuthorsGómez-Zavaglia, A, Kaczor, A, Almeida, R, Cristiano, MLS, Fausto, R
Year of Publication2008
JournalJ Phys Chem A
Volume112
Issue8
Date Published2008 Feb 28
Pagination1762-72
ISSN1520-5215
KeywordsCarbohydrates, Gases, Krypton, Models, Chemical, Models, Molecular, Molecular Conformation, Molecular Structure, Oxides, Software, Spectrophotometry, Infrared, Temperature, Thermodynamics, Thiazoles
Abstract

In this work, the conformational space of the pseudosaccharyl ether 3-(allyloxy)-1,2-benzisothiazole 1,1-dioxide (ABID) has been studied by means of infrared spectroscopy and density functional theory (DFT) calculations. Five different low energy conformers (TSk, TC, GSk, GSk' and GC, with relative energies of 0.00, 1.97, 2.00, 3.82 and 6.02 kJ mol(-1), respectively) were found on the DFT(B3LYP)/6-311++G(3df,3pd) potential energy surface of the molecule, all of them differing in the conformation of the allyl substituent. According to the calculations, in the gaseous phase all conformers are significantly populated (TSk:TC:GSk:GSk':GC = 47%:16%:18%:12%:7%, at 350 K). In the cryogenic matrices, however, only the TSk and TC conformers exist due to isomerization from the higher energy gauche forms to the most stable trans isomers during deposition of the matrix (conformational cooling). The observed conformational cooling is in consonance with the low calculated energy barriers for the GSk --> TSk, GSk' --> TSk and GC --> TC isomerization processes. Results from annealing experiments in krypton matrix doubtlessly show that in this matrix the order of stability of the TSk and TC conformers is reversed, with the more planar TC form becoming the most stable conformer.

DOI10.1021/jp0770918
Sapientia

http://www.ncbi.nlm.nih.gov/pubmed/18237158?dopt=Abstract

Alternate JournalJ Phys Chem A
PubMed ID18237158