Infrared and theoretical calculations in 2-halocycloheptanones conformational analysis

Author(s)

Rozada, Thiago C. ^[1] ; Gauze, Gisele F. ^[1] ; Favaro, Denize C. ^[2] ; Rittner, Roberto ^[2] ; Basso, Ernani A. ^[1]

Affiliation

^[1] Univ Estadual Maringa, Dept Quim, BR-87020900 Maringa, PR - Brazil

^[2] Univ Estadual Campinas, Inst Quim, BR-13083970 Campinas, SP - Brazil

• Document type: Journal article
• Source: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY; v. 94, p. 277-287, AUG 2012.
• Web of Science Citations: 4

Abstract

2-Halocycloheptanones (Halo = F, Cl, Br and I) were synthesized and their conformational analysis was performed through infrared spectroscopy data. The corresponding conformers geometries and energies were obtained by theoretical calculations at B3LYP/aug-cc-pVDZ level of theory in the isolated state and in solution. It was observed, by both approaches, that the conformational preferences were very sensitive to the solvent polarity, since its increase led to an increase in the population of the more polar conformer. An analysis of these conformational equilibria showed they suffer also the influence of stereoelectronic effects, like hyperconjugation and steric effects. These results were interpreted using natural bond orbital (NBO) analysis, which indicated that the electronic delocalization to the orbital pi{*}c=o is directly involved in the stability increase of conformers I and II. The relative effect of the period of the halogen can also be noted, with changes in the conformational preferences and in the energies involved in the interactions of NBO. (C) 2012 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 05/59649-0 - Conformational equilibria studies by nuclear magnetic resonance spectroscopy, infrared spectroscopy and theoretical calculations
• Grantee: Roberto Rittner Neto
• Support Opportunities: Research Projects - Thematic Grants