School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, UK.
Phys Chem Chem Phys. 2018 Jun 6;20(22):15380-15388. doi: 10.1039/c8cp02444h.
We report a set of theoretical calculations designed to examine the potential of model uranyl complexes to participate in hydrogen- and halogen-bonding. Potential energy scans for the interaction of [UO2Cl2(H2O)3] and [UO2(NCSe)2(H2O)3] with a single water molecule demonstrate that uranyl is a weak hydrogen bond acceptor, but that equatorially coordinated water is a strong hydrogen bond donor. These predictions are supported by a survey of contacts reported in the Cambridge Structural Database. At the minima of each scan, we show that the interaction energy is only weakly dependent on the choice of the theoretical method, with standard density functional theory methods comparing well with coupled-cluster, MP2 and double-hybrid DFT predictions. Geometry optimisation of a 1 : 1 uranyl : water complex results in a cyclic structure, in which vibrational frequencies, atoms-in-molecules and natural bond orbital analysis support the weakness of U-Oyl as an acceptor. The origin of this behaviour is traced to the electronic structure of uranyl, and in particular covalency in the U-Oyl bonds resulting from donation into formally empty 5f and 6d orbitals on U.
我们报告了一组理论计算，旨在研究模型铀酰配合物参与氢键和卤键的潜力。与单个水分子相互作用的[UO2Cl2（H2O）3]和[UO2（NCSe）2（H2O）3]的势能扫描表明，铀酰是弱氢键受体，但赤道配位的水分子是强氢键供体。这些预测得到了剑桥结构数据库中报道的接触调查的支持。在每个扫描的最小值处，我们表明相互作用能仅与理论方法的选择弱相关，标准密度泛函理论方法与耦合簇、MP2 和双杂交 DFT 预测相当。铀酰与水的 1:1 配合物的几何优化产生了一个环状结构，其中振动频率、原子在分子中和自然键轨道分析支持 U-Oyl 作为受体的弱性。这种行为的起源可以追溯到铀酰的电子结构，特别是由于 U 上的 5f 和 6d 轨道上的形式空轨道向 U-Oyl 键的捐赠导致的共价性。
