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首页> 外文期刊>Chemistry: A European journal >Creating sigma-Holes through the Formation of Beryllium Bonds
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Creating sigma-Holes through the Formation of Beryllium Bonds

机译：通过形成铍键创建Sigma-Holes

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Through the use of ab initio theoretical models based on MP2/aug-cc-pVDZ-optimized geometries and CCSD(T)/aug-cc-pVTZ and CCSD(T)/aug-c-pVDZ total energies, it has been shown that the significant electron density rearrangements that follow the formation of a beryllium bond may lead to the appearance of a sigma-hole in systems that previously do not exhibit this feature, such as CH3OF, NO2F, NO3F, and other fluorine-containing systems. The creation of the sigma-hole is another manifestation of the bond activation-reinforcement (BAR) rule. The appearance of a sigma-hole on the F atoms of CH3OF is due to the enhancement of the electronegativity of the O atom that participates in the beryllium bond. This atom recovers part of the charge transferred to Be by polarizing the valence density of the F into the bonding region. An analysis of the electron density shows that indeed this bond becomes reinforced, but the F atom becomes more electron deficient with the appearance of the sigma-hole. Importantly, similar effects are also observed even when the atom participating in the beryllium bond is not directly attached to the F atom, as in NO2F, NO3F, or NCF. Hence, whereas the isolated CH3OF, NO2F, and NO3F are unable to yield FBase halogen bonds, their complexes with BeX2 derivatives are able to yield such bonds. Significant cooperative effects between the new halogen bond and the beryllium bond reinforce the strength of both noncovalent interactions.
机译：通过使用基于MP2 / aug-cc-pVDZ优化的几何形状和CCSD（T）/ aug-cc-pVTZ和CCSD（T）/ aug-c-pVDZ总能量的从头算理论模型，已证明，在铍键形成之后发生的显着电子密度重排可能导致在以前不具有此功能的系统（例如CH3OF，NO2F，NO3F和其他含氟系统）中出现sigma-hole。 σ孔的创建是键激活-增强（BAR）规则的另一种体现。 CH3OF的F原子上出现sigma-hole是由于提高了参与铍键的O原子的电负性。该原子通过使F的化合价极化进入键合区域来回收转移给Be的部分电荷。对电子密度的分析表明，该键确实得到了增强，但是F原子随着sigma-hole的出现而变得更加缺乏电子。重要的是，即使参与铍键的原子没有直接连接到F原子上（如NO2F，NO3F或NCF），也观察到类似的效果。因此，尽管分离出的CH3OF，NO2F和NO3F无法产生FBase卤素键，但它们与BeX2衍生物的配合物却能够产生这种键。新的卤素键和铍键之间的重要协同作用增强了这两种非共价相互作用的强度。

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