Vermeeren Pascal, Brinkhuis Francine, Hamlin Trevor A, Bickelhaupt F Matthias
Department of Theoretical Chemistry Amsterdam Institute of Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam (The, Netherlands.
Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen (The, Netherlands.
Chem Asian J. 2020 Apr 1;15(7):1167-1174. doi: 10.1002/asia.202000009. Epub 2020 Mar 9.
We have quantum chemically studied alkali cation-catalyzed aromatic Diels-Alder reactions between benzene and acetylene forming barrelene using relativistic, dispersion-corrected density functional theory. The alkali cation-catalyzed aromatic Diels-Alder reactions are accelerated by up to 5 orders of magnitude relative to the uncatalyzed reaction and the reaction barrier increases along the series Li < Na < K < Rb < Cs < none. Our detailed activation strain and molecular-orbital bonding analyses reveal that the alkali cations lower the aromatic Diels-Alder reaction barrier by reducing the Pauli repulsion between the closed-shell filled orbitals of the dienophile and the aromatic diene. We argue that such Pauli mechanism behind Lewis-acid catalysis is a more general phenomenon. Also, our results may be of direct importance for a more complete understanding of the network of competing mechanisms towards the formation of polycyclic aromatic hydrocarbons (PAHs) in an astrochemical context.
我们使用相对论性、色散校正密度泛函理论，对碱金属阳离子催化的苯与乙炔之间形成桶烯的芳香狄尔斯-阿尔德反应进行了量子化学研究。相对于未催化的反应，碱金属阳离子催化的芳香狄尔斯-阿尔德反应加速了高达5个数量级，并且反应势垒沿Li < Na < K < Rb < Cs < 无此催化的顺序增加。我们详细的活化应变和分子轨道键合分析表明，碱金属阳离子通过减少亲双烯体和芳香二烯的闭壳层填充轨道之间的泡利排斥，降低了芳香狄尔斯-阿尔德反应势垒。我们认为，这种路易斯酸催化背后的泡利机制是一种更普遍的现象。此外，我们的结果对于更全面地理解天体化学背景下多环芳烃（PAHs）形成的竞争机制网络可能具有直接重要性。
