Aprà Edoardo, Warneke Jonas, Xantheas Sotiris S, Wang Xue-Bin
Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P. O. Box 999, Richland, Washington 99352, USA.
Physical Sciences Division, Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, MSIN K8-88, Richland, Washington 99352, USA.
J Chem Phys. 2019 Apr 28;150(16):164306. doi: 10.1063/1.5089510.
We report a joint benchmark study on the electronic stability of closo-dodecaborate [BH] employing negative ion photoelectron spectroscopy and high level electronic structure methods. The photoelectron spectra of [BH], measured at 266, 193, and 157 nm, yield the Adiabatic and Vertical Detachment Energies (ADE and VDE) of this dianion at 0.93 ± 0.05 eV and 1.15 ± 0.05 eV, respectively, along with a ∼3 eV Repulsive Coulomb Barrier (RCB) against electron detachment. Theoretical calculations at various levels of electronic structure theory confirm the high stability of this dianion. The ADE and VDE values calculated at the coupled cluster with single, double and a perturbative estimate of triple excitations/aug-cc-PVQZ level are 0.92 and 1.16 eV, in excellent agreement with the experimental benchmark values. The comparison between the experimental and the theoretical values obtained at different levels of theory indicate that the PBE0 density functional represents a cost-effective method of sufficient accuracy to describe the molecular properties of this dianion and associated compounds. The theoretical RCB was modeled after the electrostatic potential (ESP) and point charge method (PCM) along three different detachment pathways, viz., along the B-H bond, perpendicular to a B-B bond, and normal to a B-B-B triangle. It was found that detachment of the electron along the B-H bond is preferred, as this pathway is associated with RCBs between 2.3 eV (PCM) and 3.3 eV (ESP), values that bracket the experimental estimate of ∼3 eV.
我们报告了一项关于闭式十二硼酸盐[BH]电子稳定性的联合基准研究，采用负离子光电子能谱和高水平电子结构方法。在266、193和157nm处测量的[BH]光电子能谱，分别给出了该二价阴离子的绝热和垂直脱离能（ADE和VDE）为0.93±0.05eV和1.15±0.05eV，以及约3eV的排斥库仑势垒（RCB）以阻止电子脱离。不同电子结构理论水平的理论计算证实了该二价阴离子的高稳定性。在耦合簇单双激发加微扰三重激发/aug-cc-PVQZ水平计算得到的ADE和VDE值分别为0.92和1.16eV，与实验基准值高度吻合。不同理论水平下实验值与理论值的比较表明，PBE0密度泛函是一种具有足够精度且成本效益高的方法，可用于描述该二价阴离子及相关化合物的分子性质。理论RCB是根据静电势（ESP）和点电荷方法（PCM）沿三种不同的脱离途径建模的，即沿B-H键、垂直于B-B键以及垂直于B-B-B三角形。结果发现，沿B-H键的电子脱离是首选途径，因为该途径的RCB在2.3eV（PCM）至3.3eV（ESP）之间，这些值与约3eV的实验估计值相符。
