Arene-Bridged Dithorium Complexes: Inverse Sandwiches Supported by a δ Bonding Interaction
Arene-Bridged Dithorium Complexes: Inverse Sandwiches Supported by a δ Bonding Interaction
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芳烃桥二钍配合物：δ 键相互作用支持的反三明治
DOI：
10.1021/jacs.0c11215
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发表时间：
2020
影响因子：
15
通讯作者：
Huang, Wenliang
中科院分区：
文献类型：
--
作者：
Yu, Chao;Liang, Jiefeng;Deng, Chong;Lefèvre, Guillaume;Cantat, Thibault;Diaconescu, Paula L.;Huang, Wenliang
在芳烃存在下，用钾石墨还原钍（IV）前体，合成了一系列芳烃桥联的双钍配合物。这些化合物均为反夹心结构，芳烃以μ-η6，η6-模式桥接两个钍中心。结构和光谱数据支持的两个Th（IV）离子和芳烃四阴离子，这是一个芳香族结构根据胡斯派克尔规则的分配。芳烃交换反应表明，相应化合物的稳定性顺序为萘→甲苯<苯→联苯。反应性研究表明，它们作为四电子还原剂能够还原蒽，环辛四烯，炔，偶氮苯，而单核钍蒽配合物可以还原苯。密度泛函理论计算表明，钍6d和5 f轨道与芳烃π* 轨道之间存在δ键，具有明显的共价键特征，能够稳定高度还原的芳烃配体。
A series of arene-bridged dithorium complexes was synthesized via the reduction by potassium graphite of a Th(IV) precursor in the presence of arenes. All these compounds adopt an inverse-sandwich structure, with the arene bridging two thorium centers in a μ-η6,η6-mode. Structural and spectroscopic data support the assignment of two Th(IV) ions and an arene tetraanion, which is an aromatic structure according to Hückel’s rule. Arene exchange reactions revealed that the stability of the corresponding compounds follows the series naphthalene ≪ toluene < benzene ≈ biphenyl. Reactivity studies showed that they function as four-electron reductants capable to reduce anthracene, cyclooctatetraene, alkynes, and azobenzene, while a mononuclear thorium anthracene complex could reduce benzene. Density functional theory calculations unveiled that the bonding interactions consist of δ bonds between thorium 6d and 5f orbitals and arene π* orbitals, showing a significant covalent character, able to stabilize highly reduced arene ligands.