Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA.
Institute for Quantum Science and Engineering, Texas A&M University, College Station, TX 77843-4242, USA.
Molecules. 2021 Feb 19;26(4):1106. doi: 10.3390/molecules26041106.
The conformations of 2-cyclopenten-1-ol (2CPOL) have been investigated by high-level theoretical computations and infrared spectroscopy. The six conformational minima correspond to specific values of the ring-puckering and OH internal rotation coordinates. The conformation with the lowest energy possesses intramolecular π-type hydrogen bonding. A second conformer with weaker hydrogen bonding has somewhat higher energy. Ab initio coupled-cluster theory with single and double excitations (CCSD) was used with the cc-pVTZ (triple-ζ) basis set to calculate the two-dimensional potential energy surface (PES) governing the conformational dynamics along the ring-puckering and internal rotation coordinates. The two conformers with the hydrogen bonding lie about 300 cm (0.8 kcal/mole) lower in energy than the other four conformers. The lowest energy conformation has a calculated distance of 2.68 Å from the hydrogen atom on the OH group to the middle of the C=C double bond. For the other conformers, this distance is at least 0.3 Å longer. The infrared spectrum in the O-H stretching region agrees well with the predicted frequency differences between the conformers and shows the conformers with the hydrogen bonding to have the lowest values. The infrared spectra in other regions arise mostly from the two hydrogen-bonded species.
2-环戊烯-1-醇（2CPOL）的构象已通过高级理论计算和红外光谱进行了研究。六个构象最小值对应于环扭转和 OH 内旋转坐标的特定值。能量最低的构象具有分子内 π 型氢键。具有较弱氢键的第二个构象具有略高的能量。使用带有 cc-pVTZ（三 ζ）基组的单和双激发（CCSD）从头算耦合簇理论计算了沿环扭转和内部旋转坐标控制构动态的二维势能面（PES）。具有氢键的两个构象的能量比其他四个构象低约 300 cm（0.8 kcal/mol）。能量最低的构象中，OH 基团上的氢原子到 C=C 双键中间的距离计算为 2.68 Å。对于其他构象，此距离至少长 0.3 Å。O-H 伸缩区域的红外光谱与预测的构象之间的频率差非常吻合，并显示具有氢键的构象具有最低值。其他区域的红外光谱主要来自两种氢键物种。
