Esselman Brian J, Zdanovskaia Maria A, Owen Andrew N, Stanton John F, Woods R Claude, McMahon Robert J
Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706-1322, United States.
Quantum Theory Project, Departments of Physics and Chemistry, University of Florida, Gainesville, Florida 32611, United States.
J Am Chem Soc. 2023 Oct 11;145(40):21785-21797. doi: 10.1021/jacs.3c03109. Epub 2023 Sep 29.
Recent advances in gas-phase structure determination afford outstanding agreement between the CCSD(T)/cc-pCVTZ-corrected semi-experimental () equilibrium structures and their corresponding best theoretical estimates (BTEs) of the equilibrium structures () based upon corrections to the CCSD(T)/cc-pCV5Z geometries for the aromatic heterocycles pyrimidine and pyridazine. Herein, that same analysis is extended to the fundamental aromatic molecule benzene, using published experimental spectroscopic data for a total of 11 available isotopologues. The incorporation of rotational constants from all of these isotopologues and CCSD(T) corrections to address the impacts of both the vibration-rotation interaction and electron-mass distribution results in a highly precise and accurate structure. The CCSD(T)/cc-pCV5Z optimized geometry has been further corrected to address a finite basis set, untreated electron correlation, relativistic effects, and a breakdown of the Born-Oppenheimer approximation. This analysis achieves outstanding agreement between the (BTE) and structural parameters of benzene to a highly satisfying level (0.0001 Å), an agreement that surpasses our recently published structures of the aforementioned nitrogen-substituted benzene analogues. The geometry of benzene is now known to an unprecedented precision: = 1.3913 (1) Å and = 1.0809 (1) Å. The mutual agreement between theory and experiment presented in this work validates both, substantially resolving all discrepancies between the and theoretical structures available in the literature.
气相结构测定的最新进展使得基于对嘧啶和哒嗪等芳香杂环的CCSD(T)/cc-pCV5Z几何结构进行校正后得到的CCSD(T)/cc-pCVTZ校正半实验平衡结构与它们相应的平衡结构最佳理论估计值（BTEs）之间达成了出色的一致性。在此，利用总共11种可用同位素异构体的已发表实验光谱数据，将相同的分析扩展到基本芳香分子苯。纳入所有这些同位素异构体的转动常数以及CCSD(T)校正以解决振动-转动相互作用和电子质量分布的影响，从而得到了高精度和准确的结构。CCSD(T)/cc-pCV5Z优化几何结构已进一步校正，以解决有限基组、未处理的电子相关、相对论效应以及玻恩-奥本海默近似的失效问题。该分析使得苯的BTE结构参数与实验结构之间达成了高度令人满意的一致性水平（0.0001 Å），这一一致性超过了我们最近发表的上述氮取代苯类似物的结构。现在已知苯的几何结构达到了前所未有的精度： = 1.3913 (1) Å和 = 1.0809 (1) Å。这项工作中理论与实验之间的相互一致性验证了两者，基本解决了文献中可用的实验结构与理论结构之间的所有差异。
