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Spectroscopic and theoretical studies of some 2-(methoxy)-2-[(4-substituted)-phenylsulfany1]-(4 `-substituted) acetophenones

Texto completo
Traesel, Henrique J. [1] ; Olivato, Paulo R. [1] ; Rodrigues, Daniel N. S. [1] ; Valenca, Jessica [1] ; Rodrigues, Alessandro [2] ; Zukerman-Schpector, Julio [3] ; Dal Colle, Maurizio [4]
Número total de Autores: 7
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, Inst Chem, Conformat Anal & Elect Interact Lab, CP 26077, BR-05513970 Sao Paulo, SP - Brazil
[2] Univ Fed Sao Paulo, UNIFESP, Dept Chem, BR-09972270 Diadema, SP - Brazil
[3] Univ Fed Sao Carlos, Dept Chem, CP 676, BR-13565905 Sao Carlos, SP - Brazil
[4] Univ Ferrara, Dipartimento Sci Chim & Farmaceut, I-44121 Ferraro - Italy
Número total de Afiliações: 4
Tipo de documento: Artigo Científico
Citações Web of Science: 0

The conformational analysis of some 2-(methoxy)-2-{[}(4-substituted)-phenylsulfany1]-(4'-substituted) acetophenones was performed through infrared (IR) spectroscopic analysis of the carbonyl stretching band (nu(co)), supported by B3LYP/6-31+G(d,p) calculations and X-ray diffraction. Five (1-5) of the seven studied compounds (1-7) presented Fermi resonance (FR) on the vco fundamental transition band. Deuteration of these compounds (1a-5a) precluded the occurrence of FR, revealing a vco doublet for all compounds in all solvents used. The computational results indicated the existence of three conformers (c(1), c(2) and c(3)) for the whole series whose relative abundances varied with solvent permittivity. The higher vco frequency c(1) conformer was assigned to the higher frequency component of the carbonyl doublet, while both c(2) and c(3) were assigned to the lower frequency one. Anharmonic vibrational frequencies and Potential Energy Distribution (PED) calculations of compound 3 indicated that the combination band (cb) between the methyne delta(CH) and one skeletal mode couples with the v(co) mode giving rise to the FR on the c(2) conformer in vacuum and on the c(1) one in non-polar solvents. The experimental data indicated a progressive increase in c(1) conformer stability with the increase of the solvent dielectric constant, which is in good agreement with the polarizable continuum model (PCM) calculations. The higher vco frequency and the stronger solvation of the c(1) conformer is a consequence of the repulsive field effect (RFE) originated by the alignment and closeness of the C delta+=O delta- and C delta+-O delta- dipoles. Finally, the balance between orbital and electrostatic interactions dictates the conformational preferences. X-ray single crystal analysis for compound 6 revealed the c(1) geometry in the solid state and its stabilization by C-H...O hydrogen bonds. (C) 2018 Published by Elsevier B.V. (AU)

Processo FAPESP: 16/21676-0 - Reações de haloaminação enantiosseletivas visando a síntese de aminodióis
Beneficiário:Alessandro Rodrigues
Linha de fomento: Auxílio à Pesquisa - Regular