Zhu Qin, Chen Shuwen, Chen Dandan, Lin Lu, Xiao Kui, Zhao Liang, Solà Miquel, Zhu Jun
State Key Laboratory of Physical Chemistry of Solid Surfaces and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Key Laboratory for Organic Electronics & Information Displays (KLOEID) and Institute of Advanced Materials (IAM), SICAM, Nanjing University of Posts & Telecommunications, Nanjing 210023, China.
Fundam Res. 2023 Apr 28;3(6):926-938. doi: 10.1016/j.fmre.2023.04.004. eCollection 2023 Nov.
Aromaticity, in general, can promote a given reaction by stabilizing a transition state or a product via a mobility of π electrons in a cyclic structure. Similarly, such a promotion could be also achieved by destabilizing an antiaromatic reactant. However, both aromaticity and transition states cannot be directly measured in experiment. Thus, computational chemistry has been becoming a key tool to understand the aromaticity-driven reaction mechanisms. In this review, we will analyze the relationship between aromaticity and reaction mechanism to highlight the importance of density functional theory calculations and present it according to an approach via either aromatizing a transition state/product or destabilizing a reactant by antiaromaticity. Specifically, we will start with a particularly challenging example of dinitrogen activation followed by other small-molecule activation, C-F bond activation, rearrangement, as well as metathesis reactions. In addition, antiaromaticity-promoted dihydrogen activation, CO capture, and oxygen reduction reactions will be also briefly discussed. Finally, caution must be cast as the magnitude of the aromaticity in the transition states is not particularly high in most cases. Thus, a proof of an adequate electron delocalization rather than a complete ring current is recommended to support the relatively weak aromaticity in these transition states.
一般来说，芳香性可以通过环状结构中π电子的移动来稳定过渡态或产物，从而促进特定反应。同样，这种促进作用也可以通过使反芳香性反应物不稳定来实现。然而，芳香性和过渡态在实验中都无法直接测量。因此，计算化学已成为理解芳香性驱动反应机制的关键工具。在这篇综述中，我们将分析芳香性与反应机制之间的关系，以突出密度泛函理论计算的重要性，并按照通过使过渡态/产物芳香化或通过反芳香性使反应物不稳定的方法来呈现。具体而言，我们将从一个特别具有挑战性的二氮活化例子开始，接着讨论其他小分子活化、C-F键活化、重排以及复分解反应。此外，还将简要讨论反芳香性促进的二氢活化、CO捕获和氧还原反应。最后，必须谨慎的是，在大多数情况下，过渡态中的芳香性程度并不是特别高。因此，建议通过充分的电子离域而非完整的环电流来证明这些过渡态中相对较弱的芳香性。
