Characterization of H–π and CH–O structures of the 1:1 methanol-benzene complex using matrix isolation infrared spectroscopy

IF 0.6 4区 物理与天体物理 Q4 PHYSICS, APPLIED
Jay C. Amicangelo, Natalie C. Romano, Geoffrey R. Demay, Ian E. Campbell, Joshua D. Wilkins
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引用次数: 0

Abstract

Matrix isolation infrared spectroscopy was used to characterize a 1:1 complex of methanol (CH3OH) and benzene (C6H6). Co-deposition experiments with CH3OH and C6H6 were performed at 17–20 K using nitrogen and argon as the matrix gases. Several new infrared peaks in the co-deposition spectra were observed near the fundamental absorptions of the CH3OH and C6H6 parent molecules and these new peaks have been attributed to CH3OH–C6H6 complexe. Experiments were also performed with isotopic CD3OD and C6D6 and the corresponding infrared peaks of the isotopologue complexes have also been observed. Theoretical calculations were performed for the CH3OH–C6H6 complex using the M06-2X, ωB97X-D, MP2, and CCSD(T) methods with the aug-cc-pVDZ and aug-cc-pVTZ basis sets. Full geometry optimizations followed by vibrational frequency calculations were performed for several initial starting geometries and three stable minima were found for the CH3OH–C6H6 complex. The first has the CH3OH above the C6H6 ring with the OH hydrogen interacting with the π cloud of the ring (H–π complex), the second has the CH3OH above the C6H6 ring with the OH oxygen interacting with one or two of the C–H bonds of the ring (CH–O 1 complex), and the third has the CH3OH towards the side of the C6H6 ring with the OH oxygen interacting with two of the C–H bonds of the ring (CH–O 2 complex). The H–π complex structure is predicted to be the lower energy structure by ∼8 kJ/mol compared to the two CH–O structures. Comparing the theoretically predicted infrared spectra for the optimized CH3OH–C6H6 complex structures to the experimentally observed infrared peaks in argon and nitrogen matrices, it is concluded that in the argon matrices only the H–π complex structure is being observed, whereas in the nitrogen matrices the H–π complex and CH–O 1 complex structures are being observed.
利用基质分离红外光谱鉴定 1:1 甲醇-苯复合物的 H-π 和 CH-O 结构
基质分离红外光谱法用于表征甲醇(CH3OH)和苯(C6H6)的 1:1 复合物。以氮气和氩气为基质气体,在 17-20 K 的温度下进行了 CH3OH 和 C6H6 的共沉积实验。在共沉积光谱中,在 CH3OH 和 C6H6 母分子的基吸收附近观察到了几个新的红外峰,这些新峰被归因于 CH3OH-C6H6 复合物。还用同位素 CD3OD 和 C6D6 进行了实验,也观察到了同位素络合物的相应红外峰。我们使用 M06-2X、ωB97X-D、MP2 和 CCSD(T) 方法以及 aug-cc-pVDZ 和 aug-cc-pVTZ 基集对 CH3OH-C6H6 复合物进行了理论计算。对几种初始几何结构进行了全面的几何优化和振动频率计算,发现 CH3OH-C6H6 复合物有三个稳定的最小值。第一种是 CH3OH 位于 C6H6 环的上方,OH 氢与该环的π云相互作用(H-π 复合物);第二种是 CH3OH 位于 C6H6 环的上方,OH 氧与该环的一个或两个 C-H 键相互作用(CH-O 1 复合物);第三种是 CH3OH 位于 C6H6 环的一侧,OH 氧与该环的两个 C-H 键相互作用(CH-O 2 复合物)。据预测,与两种 CH-O 结构相比,H-π 复合物结构的能量要低∼8 kJ/mol。将优化的 CH3OH-C6H6 复合物结构的理论预测红外光谱与实验观察到的氩和氮基质中的红外峰进行比较,得出的结论是:在氩基质中只观察到 H-π 复合物结构,而在氮基质中则观察到 H-π 复合物和 CH-O 1 复合物结构。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Low Temperature Physics
Low Temperature Physics 物理-物理:应用
CiteScore
1.20
自引率
25.00%
发文量
138
审稿时长
3 months
期刊介绍: Guided by an international editorial board, Low Temperature Physics (LTP) communicates the results of important experimental and theoretical studies conducted at low temperatures. LTP offers key work in such areas as superconductivity, magnetism, lattice dynamics, quantum liquids and crystals, cryocrystals, low-dimensional and disordered systems, electronic properties of normal metals and alloys, and critical phenomena. The journal publishes original articles on new experimental and theoretical results as well as review articles, brief communications, memoirs, and biographies. Low Temperature Physics, a translation of the copyrighted Journal FIZIKA NIZKIKH TEMPERATUR, is a monthly journal containing English reports of current research in the field of the low temperature physics. The translation began with the 1975 issues. One volume is published annually beginning with the January issues.
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