Rotamer Populations and Molecular Structure of 9-Isobutyl-1,4-dimethoxytriptycene: Further Evidence for the Presence of CH<sub>3</sub>···O Hydrogen Bond
in the crystal. One of the methyl groups of the isobutyl group that directs inward relative to the triptycene skeleton, is placed very closely to the 1-methoxy-oxygen to indicate the presence of the CH3···O hydrogen bond. Implications of other structural parameters are also discussed.
标题化合物在低温下的 1 H NMR 谱表明存在 sc 构象异构体作为主要成分:对于 sc\ightleftarrowsap 平衡,ΔH°=0.9±0.3 kcal mol-1,ΔS°=5±2 cal mol-1。不同温度下光谱的线形分析为 C9–Ci-Bu 键的内旋提供了以下激活参数:ΔH\eweq=8.8±0.3 kcal mol-1, ΔS\eweq=-5.0±1.2 cal mol -1 K-1 用于 ap→sc 过程。该化合物的 X 射线晶体学显示该分子作为晶体中的 sc 构象异构体存在。异丁基中相对于三苯乙烯骨架向内定向的甲基之一与 1-甲氧基-氧非常接近,以指示 CH3…O 氢键的存在。还讨论了其他结构参数的含义。
Liebermann, Justus Liebigs Annalen der Chemie, 1882, vol. 212, p. 107
作者:Liebermann
DOI:——
日期:——
Griendt, Freek van de; Cerfontain, Hans, Journal of the Chemical Society. Perkin transactions II, 1980, p. 13 - 18