Effect of bond orbital interactions on the conformational stabilities of 1,2-difluoroethane and 2,3-difluorobutanes
2019
Hayashi, Nobuyuki | Ujihara, Tomomi | Ikeda, Hirotaka
Several hypotheses have been proposed to explain the origin of the conformational stabilities of 1,2-difluoroalkanes, for which bond orbital interactions are an important factor. However, there is a limit to the effectiveness of the traditional approach focusing on only the antiperiplanar interactions between bonding and antibonding orbitals such as σC–H/σC–F*, σC–C/σC–F*, and σC–F/σC–F*, which cannot actually explain the conformational stabilities of 2,3-difuluorobutanes. In this study, to elucidate the effect of bond orbital interactions on the conformational stabilities of 1,2-difluoroethane, erythro-2,3-difluorobutane, and threo-2,3-difluorobutane, we extended the range of interactions considered to beyond these conventional interactions. The results showed that for 1,2-difluoroethane, the conformational stability can be understood by considering all antiperiplanar bond orbital interactions around the C1–C2 bond, and for 2,3-difluorobutanes, by considering all antiperiplanar bond orbital interactions around the C2–C3 bond in addition to bond orbital interactions between the methyl groups.
显示更多 [+] 显示较少 [-]