Infrared and theoretical calculations in 2-halocycloheptanones conformational analysis

详细信息	查看全文 | 推荐本文 |

• 作者：Thiago C. Rozada^a ; Gisele F. Gauze^a ; Denize C. Favaro^b ; Roberto Rittner^b ; Ernani A. Basso^a ; ^{eabasso@uem.br}
• 关键词：2-Halocycloheptanones ; Conformation analyses ; Infrared ; Theoretical calculations ; NBO
• 刊名：Spectrochimica Acta Part A ; Molecular and Biomolecular Spectroscopy
• 出版年：2012
• 期刊代码：99_13861425
• 类别：ch
• 出版时间：August, 2012
• 卷：94
• 期：Complete
• 页码：277-287
• 文件大小：1453 K

摘要

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 蟺*_CO 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.