Spectroscopic and theoretical studies of some N,N-diethyl-2-[(4 '-substituted)phenylsulfonyl]acetamides

Spectroscopic and theoretical studies of some N,N-diethyl-2-[(4 '-substituted)phenylsulfonyl]acetamides

Author Vinhato, Elisangela Google Scholar
Olivato, Paulo R. Google Scholar
Rodrigues, Alessandro Autor UNIFESP Google Scholar
Zukerman-Schpector, Julio Google Scholar
Dal Colle, Maurizio Google Scholar
Institution Universidade de São Paulo (USP)
Universidade Federal de São Paulo (UNIFESP)
Universidade Federal de São Carlos (UFSCar)
Univ Ferrara
Abstract The analysis of the IR carbonyl band of the N,N-diethyl-2-[(4'-substituted)phenylsulfonyl]acetamides Et(2)NC(O)CH(2)S(O)(2)-C(6)H(4)-Y (Y = OMe 1, Me 2,1-13, Cl 4, Br 5, NO(2) 6) supported by B3LYP/6-31G(d,p) calculations for 3, indicated the existence of three pairs (anti and syn) of cis (c) and gauche (g(1) and g(2)) conformers in the gas phase, being the gauche conformers significantly more stable than the cis ones. the anti geometry is more stable than the syn one, for each pair of cis and gauche conformers. the summing up of the orbital (NBO analysis) and electrostatic interactions justifies quite well the populations and the v(CO) frequencies of the anti and syn pairs of c, g(1) and g(2) conformers. the IR higher carbonyl frequency component whose population is ca. 10%, in CCl(4), may be ascribed to the least stable and most polar cis conformer pair (in the gas phase) and the lower frequency component whose population is ca. 90%, to the summing up of the populations of the two most stable and least polar gauche conformer pairs (g(1) and g(2)) (in the gas phase). the reversal of the cis(c)/gauche (g(1) + g(2)) population ratio observed in chloroform ca. 60% (cis)/40% (gauche) and the occurrence of the most polar cis(c) conformer only, in acetonitrile, strongly suggests the coalescence of the two gauche components in a unique carbonyl band in solution. A further support to this rationalization is given by the single point PCM solvation model performed by HF/6-31G(d,p) method, which showed a progressive increase of the c/(g(1) + g(2)) ratio going from gas to CCl(4), to CHCl(3) and to CH(3)CN. X-ray single crystal analysis of 4 indicates that this compound assumes, in the solid state, the syn-clinal (gauche) conformation with respect to the [O=C-CH(2)-S] moiety, and the most stable anti geometry relative to the [C(O)N(CH(2)CH(3))(2)] fragment. in order to obtain larger energy gain from the crystal packing the molecules of 4 are linked in centrosymmetric dimers through two C-H center dot center dot center dot O interactions (C-H([O-Ph])center dot center dot center dot O([SO2])) forming a step ladder. (C) 2011 Elsevier B.V. All rights reserved.
Keywords Conformational analysis
Infrared spectroscopy
Theoretical calculations
X-ray diffraction analysis
N,N-diethyl-2-[(4 '-substituted)phenylsulfonyl]acetamides
Language English
Sponsor Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
University of Ferrara
Date 2011-09-14
Published in Journal of Molecular Structure. Amsterdam: Elsevier B.V., v. 1002, n. 1-3, p. 97-106, 2011.
ISSN 0022-2860 (Sherpa/Romeo, impact factor)
Publisher Elsevier B.V.
Extent 97-106
Origin http://dx.doi.org/10.1016/j.molstruc.2011.06.051
Access rights Closed access
Type Article
Web of Science ID WOS:000295110100014
URI http://repositorio.unifesp.br/handle/11600/34047

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