Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849-5312, USA.
Molecules. 2023 Jun 12;28(12):4712. doi: 10.3390/molecules28124712.
Positively charged metal-ammonia complexes are known to host peripheral, diffuse electrons around their molecular skeleton. The resulting neutral species form materials known as expanded or liquid metals. Alkali, alkaline earth, and transition metals have been investigated previously in experimental and theoretical studies of both the gas and condensed phase. This work is the first ab initio exploration of an -block metal-ammonia complex. The ground and excited states are calculated for Th complexes with ammonia, crown ethers, and aza-crown ethers. For Th complexes, the one valence electron Th populates the metal's 6 or 7 orbitals. For Th, the additional electrons prefer occupation of the outer s- and p-type orbitals of the complex, except Th(NH), which uniquely places all four electrons in outer orbitals of the complex. Although thorium coordinates up to ten ammonia ligands, octa-coordinated complexes are more stable. Crown ether complexes have a similar electronic spectrum to ammonia complexes, but excitations of electrons in the outer orbitals of the complex are higher in energy. Aza-crown ethers disfavor the orbitals perpendicular to the crowns, attributed to the N-H bonds pointing along the plane of the crowns.
已知带正电荷的金属-氨络合物在其分子骨架周围具有外围弥散电子。由此产生的中性物质形成了所谓的扩展或液态金属。碱金属、碱土金属和过渡金属在气体和凝聚相的实验和理论研究中都有被研究过。这项工作是首次对 - 族金属-氨络合物进行从头计算探索。计算了 Th 与氨、冠醚和氮杂冠醚络合物的基态和激发态。对于 Th 络合物，一个价电子 Th 填充在金属的 6 或 7 个轨道中。对于 Th 来说，额外的电子更喜欢占据络合物的外部 s 和 p 型轨道，除了 Th(NH)，它独特地将所有四个电子都放置在络合物的外部轨道中。尽管钍可以配位多达十个氨配体，但八配位络合物更稳定。冠醚络合物具有与氨络合物相似的电子光谱，但络合物外部轨道中的电子激发能量更高。氮杂冠醚不利于与冠醚垂直的轨道，这归因于 N-H 键沿冠醚的平面指向。
