1,3-Dimethyl-3-silapiperidine: Synthesis, Molecular Structure, and Conformational Analysis by Gas-Phase Electron Diffraction, Low Temperature NMR, IR and Raman Spectroscopy, and Quantum Chemical Calculations
作者:Bagrat A. Shainyan、Svetlana V. Kirpichenko、Erich Kleinpeter、Sergey A. Shlykov、Dmitriy Yu. Osadchiy、Nina N. Chipanina、Larisa P. Oznobikhina
DOI:10.1021/jo400289g
日期:2013.4.19
conformational properties were studied by gas-phase electron diffraction (GED), low temperature NMR, IR and Raman spectroscopy and quantum chemical calculations. The compound exists as a mixture of two conformers possessing the chair conformation with the equatorial NMe group and differing by axial or equatorial position of the SiMe group. In the gas phase, the SiMeax conformer predominates (GED: ax/eq = 65(7):35(7)%
合成了第一个含Si-H的氮杂硅杂环,1,3-二甲基-3-硅哌啶1,并通过气相电子衍射(GED),低温NMR,IR和拉曼光谱研究了其分子结构和构象性质。和量子化学计算。该化合物以两个构象异构体的混合物形式存在,这些构象异构体与赤道NMe基团具有椅子构象,并且在SiMe基团的轴向或赤道位置上不同。在气相中,森达斧构象异构体占优势(GED:AX /当量= 65(7):35(7)%,Δ ģ = 0.36(18)千卡/摩尔; IR:AX /当量= 62(5): 38(5)%,ΔG= 0.16(7)kcal / mol)。在溶液中,在143 K时,SiMe eq构象异构体在冷冻平衡中占主导地位(NMR:ax / eq = 31.5(1.5):68.5(1.5)%,ΔG = -0.22(2)kcal / mol)。确定了环反转的热力学参数(ΔG ‡ = 8.9–9.0 kcal / mol,ΔH ‡ =