College of Chemistry, Sichuan University, Chengdu 610064, China.
Inorg Chem. 2023 Feb 6;62(5):1978-1987. doi: 10.1021/acs.inorgchem.2c03249. Epub 2023 Jan 23.
The low-lying excited-state properties of the water-solvated UOCl complexes, i.e., (HO)UOCl ( = 1-3), below 33,000 cm, are investigated based on the ab initio NEVPT2 and CCSD(T) with inclusion of scalar relativistic and spin-orbit coupling effects. The simulated luminescence spectral curves agree well with the experimental spectrum in aqueous solution at -120 °C. Water coordination is found to significantly affect the character of luminescent state, which is changed from the Φ state in UOCl to the Δ state in (HO)UOCl. This is distinctly different from the observed unchanged nature of luminescent state in the cases of Ar coordination to UOCl and HO coordination to UOF in the previous work. Furthermore, by combining with the theoretical results for the solvated UOF system, the reason why water coordination does not remarkably change the spectral shape of UOCl, as opposed to UOF, was explained based on the analysis of two key spectral parameters, O-U-O symmetrical vibrational frequency and U-O bond length elongation. The roles of ligand field and spin-orbit coupling in the determination of luminescent state character and spectral shape in uranyl dihalide complexes are deeply discussed and summarized. These results deepen our understanding of the luminescent properties of uranyl complexes in aqueous solution.
基于从头算 NEVPT2 和 CCSD(T)方法，并考虑了标量相对论和自旋轨道耦合效应，研究了水合 UOCl 配合物（即（HO）UOCl（=1-3））在 33000cm 以下的低激发态性质。模拟的发光光谱曲线与-120°C 水溶液中的实验光谱吻合良好。水配位显著影响发光态的性质，这与在之前的工作中观察到的 UOCl 被 Ar 配位和 HO 配位到 UOF 时发光态不变的性质明显不同。此外，通过与溶剂化 UOF 体系的理论结果相结合，基于对两个关键光谱参数，即 O-U-O 对称振动频率和 U-O 键长伸长的分析，解释了为什么水配位不会显著改变 UOCl 的光谱形状，而不是 UOF。深入讨论和总结了配体场和自旋轨道耦合在确定铀酰二卤化物配合物发光态性质和光谱形状中的作用。这些结果加深了我们对水溶液中铀酰配合物发光性质的理解。
