Spectroscopic and theoretical studies of some 2-substituted N-methoxy-N-methyl-amides

Spectroscopic and theoretical studies of some 2-substituted N-methoxy-N-methyl-amides

Author Olivato, Paulo R. Google Scholar
Gomes, Roberto da Silva Google Scholar
Rodrigues, Alessandro Autor UNIFESP Google Scholar
Domingues, Nelson L. C. Google Scholar
Rittner, Roberto Google Scholar
Dal Colle, Maurizio Google Scholar
Institution Universidade de São Paulo (USP)
Universidade Federal de São Paulo (UNIFESP)
Fundacao Univ Fed Grande Dourados
Universidade Estadual de Campinas (UNICAMP)
Univ Ferrara
Abstract B3LYP/6-311++G(3df,3pd) calculations along with the NBO analysis of some 2-substituted N-methoxy-N-methyl-amides Y-C(R)(2)C(O)N(OMe)Me [Y = Br 1, SEt 2, SePh 4 (for R = H) and SEt 3 (for R = Me)] indicated the existence of three conformers for 1, 2, 4, namely one cis (c) and two gauche (g(1), g(2)), and two gauche (g(1), g(2)) forms for 3. the g(1) conformer is the most stable and the least polar for all derivatives, while the c one is the most polar for 1, 2 and 4. As far as the stability is concerned, the g(2) conformer is more abundant with respect to the c one for compounds 1 and 2, and slightly less stable than c for 4. for the derivative 3, the g(1) conformer is more stable and slightly less polar than the g(2) one. Moreover, the computed (nu(co)) frequencies and the relative populations of the two forms correlate quite well with the IR (nu(co)) doublet frequency components and their relative intensities in solution.The occurrence of Fermi resonance in the fundamental nu(co) region, in solution, precludes the estimative of the relative populations of the c, g(1), g(2) conformers for 1, 2 and 4. NBO analysis showed that the n(N) -> pi(center dot)(co) orbital interaction is the main factor which stabilizes the gauche (g(1), g(2)) conformers into a larger extent relative to the cis (c) one for 1, 2, 4. for these compounds along with the 3 derivative, the same interaction stabilizes more the g(1) conformer than the g(2) one. the sum of the orbital interactions from NBO analysis and the trend of the electrostatic interactions justifies quite well the populations of the (c) and gauche (g(1), g(2)) conformers for 1, 2 and 4, along with the (g(1), g(2)) conformers populations for 3 found in the gas phase. (C) 2012 Elsevier B.V. All rights reserved.
Keywords Conformational analysis
Infrared spectroscopy
Theoretical calculations
2-Substituted N-methoxy-N-methyl amides
Language English
Sponsor Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
MIUR
Date 2013-01-16
Published in Journal of Molecular Structure. Amsterdam: Elsevier B.V., v. 1031, p. 91-103, 2013.
ISSN 0022-2860 (Sherpa/Romeo, impact factor)
Publisher Elsevier B.V.
Extent 91-103
Origin http://dx.doi.org/10.1016/j.molstruc.2012.07.005
Access rights Closed access
Type Article
Web of Science ID WOS:000312686000014
URI http://repositorio.unifesp.br/handle/11600/35882

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