Zhu Zhaoguo, Marshall Mary, Harris Rachel M, Bowen Kit H, Vasiliu Monica, Dixon David A
Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States.
Department of Chemistry and Biochemistry, University of Alabama, Tuscaloosa, Alabama 35401, United States.
J Phys Chem A. 2021 Jan 14;125(1):258-271. doi: 10.1021/acs.jpca.0c09766. Epub 2020 Dec 16.
The observation and characterization of the anions: ThO, ThAu, and ThAuO is reported. These species were studied through a synergetic combination of anion photoelectron spectroscopy and ab initio correlated molecular orbital theory calculations at the CCSD(T) level with large correlation-consistent basis sets. To better understand the energetics and bonding in these anions and their corresponding neutrals, a range of smaller diatomic to tetratomic species were studied computationally. Correlated molecular orbital theory calculations at the CCSD(T) level showed that in most of these cases, there are close-lying anions and neutral clusters with different geometries and spin states and are consistent with the experimentally observed spectra. Thus, comparison of experimentally determined and computationally predicted vertical detachment energies and electron affinities for different optimized geometries and spin states shows excellent agreement to within 0.1 eV. The structures for both the neutrals and anions have a significant ionic component to the bonding because of the large electron affinity of the Au atom and modest ionization potentials for Th, ThO, and ThO. The analysis of the bonding for the Th-Th bonds from the molecular orbitals is consistent with this ionic model. The results show that there is a wide variation in the bond distance from 2.7 to 3.5 Å for the Th-Th bonds all of which are less than twice the atomic radius of Th of 3.6 Å. The bond distances encompass bond orders from 4 to 0. There can be different bond orders for the same bond distance depending on the nature of the ionic bonding suggesting that one may not be able to correlate the bond order with the bond distance in these types of clusters. In addition, the presence of an Au atom may provide a unique probe of the bonding in such clusters because of its ability to accept an electron from clusters with modest ionization potentials.
报道了对阴离子ThO、ThAu和ThAuO的观察与表征。通过阴离子光电子能谱与从头算相关分子轨道理论计算（在CCSD(T)水平，采用大的相关一致基组）的协同结合对这些物种进行了研究。为了更好地理解这些阴离子及其相应中性物种的能量学和键合情况，对一系列较小的双原子到四原子物种进行了计算研究。CCSD(T)水平的相关分子轨道理论计算表明，在大多数情况下，存在具有不同几何结构和自旋态的紧密相邻的阴离子和中性团簇，且与实验观测光谱一致。因此，对不同优化几何结构和自旋态的实验测定和计算预测的垂直脱附能及电子亲和势进行比较，结果显示在0.1 eV范围内具有极佳的一致性。由于金原子具有较大的电子亲和势，而钍、ThO和ThO具有适度的电离势，中性物种和阴离子的结构在键合中都有显著的离子成分。从分子轨道对钍 - 钍键的键合分析与该离子模型一致。结果表明，钍 - 钍键的键长在2.7至3.5 Å之间有很大变化，所有这些键长均小于钍原子半径3.6 Å的两倍。键长涵盖了从4到0的键级。对于相同的键长，根据离子键合的性质可能存在不同的键级，这表明在这类团簇中，键级与键长可能无法建立关联。此外，金原子的存在可能因其能够从具有适度电离势的团簇中接受电子，从而为这类团簇中的键合提供独特的探针。
