Sedgi Itzhak, Kozuch Sebastian
Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 841051, Israel.
Phys Chem Chem Phys. 2020 Aug 21;22(31):17725-17730. doi: 10.1039/d0cp03205k. Epub 2020 Jul 31.
The uncertainty on XeF geometry persisted for over five decades, with elusive multiple C equivalent minima as an outcome of the Jahn-Teller effect. Herein we theoretically prove that XeF shows a genuine fluorine quantum mechanical tunnelling rearrangement, rapidly "jumping" between isomers even close to 0 K. The isoelectronic anions IF and TeF behave in the same way as XeF, but with a lower and shorter energetical barrier they have a faster tunnelling rate. A complete isotopic analysis revealed a large k(F)/k(F) kinetic isotope effect. We speculate that it would be possible to experimentally observe the tunnel effect in XeF by means of cryogenic NMR or IR.
五十多年来，XeF几何结构的不确定性一直存在，由于 Jahn-Teller 效应，出现了难以捉摸的多个等效极小值。在此我们从理论上证明，XeF表现出真正的氟量子力学隧穿重排，即使在接近 0 K 时也能在异构体之间快速“跳跃”。等电子阴离子 IF 和 TeF 的行为与 XeF 相同，但由于能量势垒更低、更窄，它们的隧穿速率更快。完整的同位素分析揭示了较大的k(F)/k(F)动力学同位素效应。我们推测，通过低温核磁共振或红外光谱有可能在实验中观察到XeF中的隧道效应。
