Hu Han-Shi, Kaltsoyannis Nikolas
School of Chemistry, The University of Manchester, Oxford Road, Manchester M13 9PL, UK.
Phys Chem Chem Phys. 2017 Feb 15;19(7):5070-5076. doi: 10.1039/c7cp00113d.
Compounds featuring unsupported metal-metal bonds between actinide elements remain highly sought after yet confined experimentally to inert gas matrix studies. Notwithstanding this paucity, actinide-actinide bonding has been the subject of extensive computational research. In this contribution, high level quantum chemical calculations at both the scalar and spin-orbit levels are used to probe the Th-Th bonding in a range of zero valent systems of general formula LThThL. Several of these compounds have very short Th-Th bonds arising from a new type of Th-Th quadruple bond with a previously unreported electronic configuration featuring two unpaired electrons in 6d-based δ bonding orbitals. HAsThThAsH is found to have the shortest Th-Th bond yet reported (2.590 Å). The Th unit is a highly sensitive probe of ligand electron donor/acceptor ability; we can tune the Th-Th bond from quadruple to triple, double and single by judicious choice of the L group, up to 2.888 Å for singly-bonded ONThThNO.
含有锕系元素之间未配位金属-金属键的化合物一直备受关注，但实验上仅限于惰性气体基质研究。尽管此类研究较少，但锕系元素间的键合一直是广泛计算研究的主题。在本论文中，我们使用标量和自旋轨道水平的高水平量子化学计算方法，探究通式为LThThL的一系列零价体系中Th-Th键的情况。其中几种化合物具有非常短的Th-Th键，这源于一种新型的Th-Th四重键，其电子构型此前未被报道，在基于6d的δ键轨道中有两个未成对电子。发现HAsThThAsH具有迄今报道的最短Th-Th键（2.590 Å）。Th单元是配体电子供体/受体能力的高度敏感探针；通过明智地选择L基团，我们可以将Th-Th键从四重键调节为三重键、双键和单键，对于单键连接的ONThThNO，键长可达2.888 Å。
