Characterizing pressure-induced uranium C-H agostic bonds.
Characterizing pressure-induced uranium C-H agostic bonds.
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DOI：
10.1002/anie.201411250
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发表时间：
2015-06-01
期刊：
影响因子：
--
通讯作者：
Kaltsoyannis N
中科院分区：
文献类型：
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作者：
Arnold PL;Prescimone A;Farnaby JH;Mansell SM;Parsons S;Kaltsoyannis N
用可变高压单晶X射线晶体学和密度泛函理论研究了双铀（III）化合物[UN′′2]2（μ-η6：η6-C6 H6）（N′′=N（SiMe 3）2）.在该化合物中，低配位的金属阳离子通过π-和δ-对称的芳烃重叠偶联，并显示出与空间位阻的酰胺基配体的柔性甲基CH基团的紧密的金属=CH接触。金属-金属分离随压力的增加而减小，但最显著的结构变化是配体CH键与U中心之间的紧密接触。 虽然原子间的距离暗示了U和配体外围CH基团之间的agostic-type相互作用，但QTAIM（分子中原子的量子理论）计算分析表明，在环境压力下没有这种相互作用。然而，QTAIM和NBO分析表明，在3.2 GPa的相互作用成为agostic。
The diuranium(III) compound [UN′′2]2(μ-η6:η6-C6H6) (N′′=N(SiMe3)2) has been studied using variable, high-pressure single-crystal X-ray crystallography, and density functional theory. In this compound, the low-coordinate metal cations are coupled through π- and δ-symmetric arene overlap and show close metal=CH contacts with the flexible methyl CH groups of the sterically encumbered amido ligands. The metal–metal separation decreases with increasing pressure, but the most significant structural changes are to the close contacts between ligand CH bonds and the U centers. Although the interatomic distances are suggestive of agostic-type interactions between the U and ligand peripheral CH groups, QTAIM (quantum theory of atoms-in-molecules) computational analysis suggests that there is no such interaction at ambient pressure. However, QTAIM and NBO analyses indicate that the interaction becomes agostic at 3.2 GPa.