双核锕系元素夹心化合物及其取代物的理论与实验研究

With the development of economy, resource depletion and environmental pollution become the most challenging problems at present. As a clean and safe energy, nuclear energy has gained extensive attention all over the world. Actinide complexes can play significant roles in chemistry associated with nuclear fuel cycle. Among them, actinide sandwich-like complexes, possessing unique structures and properties, have led to the rapid growth of actinide organometallic chemistry. This project will mainly focus on theoretical studies of the binuclear actinide sandwich-like complexes and their derivatives. To explore a simple and efficient method for investigating these complexes, the isolated mononuclear actinide sandwich-like complexes will be studied firstly at different levels of theory. And then, these calculated results will be compared with the experimental results. For the equilibrium geometries of the binuclear actinide sandwich-like complexes, metal-metal multiple bonds, high-spin states and oxidation states of the actinide metal ions will be discussed by natural population analysis (NPA), natural bonding orbital (NBO) analysis as well as electron localization function (ELF) analysis. This project will put emphasis on investigating the influence of the 5f orbitals of actinide cations on chemical bonding. Meanwhile, the effects of different substitutents of ligands on the structures and properties of the binuclear actinide sandwich-like complexes will be also discussed. In addition, the possible synthetic routes and the potential applications of these binuclear actinide sandwich-like complexes will be explored by theoretical and experimental approaches. It is expected that this project will help understand the coordination modes of the actinide sandwich-like complexes as well as the effects of the 5f orbitals on chemical bonding of actinide cations. We believe that this research project can provide valuable clues for establishing the initial basis for further study on the synthesis and application of the actinide organometallic complexes.

随着传统化石能源的日渐枯竭，核能受到众多国家的重视。锕系元素化学在核.科学技术中占有非常重要的地位，对发展核化学等具有重要意义。由于锕系元素夹心型化合.物的独特结构和性质，近年来备受关注。本项目在不同理论方案下研究实验已合成且表征的.单核锕系元素夹心型化合物，并对计算结果与实验数据进行比较，优化出一套最优计算方案，从而用以理论设计及优化双核锕系元素夹心化合物及其取代物的结构。同时，利用自然布居分析、自然键轨道和电子局域函数等分析其稳定结构的金属-金属多重键，配位原子的配位方式和中心原子不同氧化态与其稳定性之间的关系。重点讨论锕系金属 5f 电子结构和不同取代基对此类化合物结构和性质的影响，预测其可能的合成路线并通过实验研究最优合成路径。本项目的完成将加深对锕系元素 5f 电子在成键中的作用和配体原子的配位方式等问题的认识，为锕系元素有机金属化合物的合成及应用开发等方面的研究奠定基础。

由于锕系元素夹心型化合物具有独特的结构和性质，近年来受到广泛关注。本项目主要采用相对论量子化学原理和方法研究锕系元素夹心化合物及其取代物。首先，在不同的理论水平下研究实验已合成且表征的单核锕系元素夹心型化合物，优化出一套适用于锕系元素夹心型化合物的最优计算方案。在此基础上，采用理论方法预测了一系列含锕系-锕系多重键的新型双核锕系元素夹心化合物，同时研究了不同价态的双核铀夹心卤化物和氰化物。利用分子轨道、自然键轨道、自然布居分析和分子中的原子量子理论等分析了此类化合物稳定结构的成键性质，重点讨论了不同取代基对此类化合物结构与性质的影响，揭示了锕系元素的5f电子在成键中的作用。通过热力学分析发现，常温下此类双核锕系元素夹心型化合物在气相中比较稳定，并提出了可能的合成路径。本项目的研究结果为今后新型锕系元素有机金属化合物的设计与合成提供了一定的理论依据。