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首页> 外文期刊>Structural Chemistry >Molecular conformational structures of 2-fluorobenzoyl chloride, 2-chlorobenzoyl chloride, and 2-bromobenzoyl chloride by gas electron diffraction and normal coordinate analysis aided by quantum chemical calculations
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Molecular conformational structures of 2-fluorobenzoyl chloride, 2-chlorobenzoyl chloride, and 2-bromobenzoyl chloride by gas electron diffraction and normal coordinate analysis aided by quantum chemical calculations

机译：借助气体电子衍射和量子化学计算辅助的正态坐标分析，对2-氟苯甲酰氯，2-氯苯甲酰氯和2-溴苯甲酰氯的分子构象结构

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摘要

The gas phase molecular structures and conformational compositions of 2-fluorobenzoyl chloride, 2-chlorobenzoyl chloride, and 2-bromobenzoyl chloride have been investigated using gas electron diffraction data obtained from experiments performed in the laboratories of the University of Oslo and Oregon State University. The refinements on the experimental data have been aided by normal coordinate calculations as well as extensive ab initio molecular orbital and density functional theory calculations up to the levels of MP4(SDQ) and B3LYP with larger basis sets up to the level of 6-311 + G(2d,p) for the computed molecular geometries, electronic energies, vibrational zero-point energies and entropy corrections, gas mixture conformational compositions, and MP2(fc) quantum mechanical force fields. The three title molecules each exist in the gas phase as two stable non-planar conformers anti and gauche with respect to the halogen atom positions with anti the lower energy conformer in each case. Among the three title molecules there have been found considerable experimental and theoretical support for several trends in molecular or conformational behavior with increasing ortho halogen atomic size: An increasing although disputable trend in the C=O bond distance values; an increasing trend in the average phenyl ring C-C bond distance values; an increasing trend in the contribution of the gauche conformer to the gaseous mixture lowering the standard free energy difference values (ΔG ~o) correspondingly; and an increasing deviation from full planarity (C _s symmetry) in both the anti and the gauche conformers of the title molecules with increasing ortho halogen atomic size. Only in the anti conformer of 2-fluorobenzoyl chloride does the experimental data refinements suggest close to full planarity for these 2-halobenzoyl chloride molecules.
机译：使用从奥斯陆大学和俄勒冈州立大学的实验室获得的气相电子衍射数据研究了2-氟苯甲酰氯，2-氯苯甲酰氯和2-溴苯甲酰氯的气相分子结构和构象组成。对实验数据的改进得益于正态坐标计算以及广泛的从头算分子轨道和密度泛函理论计算，直至MP4（SDQ）和B3LYP的水平，更大的基础设置为6-311 + G（2d，p）用于计算的分子几何形状，电子能量，振动零点能量和熵校正，气体混合物的构象组成以及MP2（fc）量子力学力场。相对于卤素原子位置，三个标题分子各自以两个稳定的非平面构象异构体存在于气相中，并且相对于卤素原子的位置具有较低的能量构象异构体。在三个标题分子中，已经发现了对邻位卤原子尺寸增加的分子或构象行为的几种趋势的大量实验和理论支持。平均苯环C-C键距离值呈上升趋势; gauche构象异构体对气体混合物贡献的增加趋势相应地降低了标准自由能差值（ΔG〜o）;随着邻卤原子原子尺寸的增加，标题分子的反构象和gauche构象与完全平面度（C s对称性）的偏差也增大。仅在2-氟苯甲酰氯的反构象异构体中，实验数据的改进表明这些2-卤代苯甲酰氯分子具有接近完全的平面度。

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