Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/56529
Type: Artigo de periódico
Title: Conformational behaviour in S-methyl halothioacetates through NMR, FT-IR, and theoretical calculations
Author: Basso, EA
Fiorin, BC
Tormena, CF
Rittner, R
Abstract: This work presents an investigation of the conformational behaviour of S-methyl chlorothioacetate (MCTA), S-methyl bromothioacetate (MBTA), and S-methyl iodothioacetate (MITA) through NMR and IR spectroscopies and through theoretical calculations that apply DFT/B3LYP theory. The DFT calculations showed two stable rotamers in the vapour phase, gauche and trans, for all the compounds. The coupling constants, (1)J(CH), were obtained from NMR spectroscopy; these were used in the solvation theory to calculate the vapour-phase energy difference, the coupling constants for each rotamer, the solution energy difference, and the rotamer population for each solvent. These data showed that for MCTA, the most stable rotamer is trans; however, for MBTA and MITA, the most stable rotamer is gauche, both in the vapour phase and in solution. The changes in rotamer stability are because of the preference in stereo-electronic interactions; in the MCTA case the interaction is mainly electrostatic, while for MBTA and MITA, it is because of the interaction between n(Br,I)-->pi(CO)(*).
Subject: S-methyl halothioacetates
conformational analysis
theoretical calculations
NMR
solvation theory
Country: Canadá
Editor: Natl Research Council Canada
Rights: fechado
Identifier DOI: 10.1139/V03-189
Date Issue: 2004
Appears in Collections:Artigos e Materiais de Revistas Científicas - Unicamp

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