The Raman and infrared spectra, ab initio calculations and spectral assignments of 1,1-dicyclopropyl-2,2-dimethylethene (c-C3H5)2C C(CH3)2
作者:Niels H. Andersen、Peter Klaeboe、Claus J. Nielsen、Brendan M. Shumberger、Gamil A. Guirgis
DOI:10.1016/j.molstruc.2019.05.108
日期:2019.11
Abstract Raman spectra of 1,1-dicyclopropyl-2,2-dimethylethene (c-C3H5)2C = C(CH3)2) as a liquid were obtained at 293 K and polarization data recorded. Additional Raman spectra were observed at various temperatures between 293 and 143 K, and intensity changes of certain bands with temperature detected. When the sample was cooled to 153 K an amorphous solid appeared; upon slow warming it turned crystalline
摘要 1,1-二环丙基-2,2-二甲基乙烯 (c-C3H5)2C = C(CH3)2) 在 293 K 下获得了拉曼光谱并记录了偏振数据。在 293 和 143 K 之间的不同温度下观察到额外的拉曼光谱,并且检测到某些波段的强度随温度的变化。当样品冷却至 153 K 时,出现无定形固体;缓慢升温后,它在 188 K 时变成结晶,并在更高的温度下熔化。在液体和无定形固体中观察到的各种主要弱带在结晶相的拉曼光谱中消失,表明在液体和无定形相中出现了两种或多种构象异构体。选定条带对的范特霍夫图显示液体中两种最丰富的构象异构体之间的焓差为 2.0 ± 0.2 kJ mol-1。在 4000-400 cm-1 区域研究了蒸气红外光谱。进行了量子化学计算以确定可能的稳定构象异构体及其振动波数、IR 和拉曼强度以及去极化特性。通过独立旋转孪生环丙基获得的势能表面扫描揭示了对称性 C2 和 C1 的两个主要构象异构体的出现,它们的焓差约为