Department of Chemistry and Biochemistry, Utah State University, Old Main Hill 300, Logan, Utah, 84322, USA.
Department of Physical and Colloid Chemistry, Peoples' Friendship University of Russia (RUDN University), 6 Miklukho-Maklaya St, Moscow, 117198, Russian Federation.
Chemistry. 2019 Apr 5;25(20):5311-5315. doi: 10.1002/chem.201806372. Epub 2019 Mar 14.
Growing demands of material science and, in particular, in the field of nonlinear optics (NLO) encourage us to look for stable highly polarizable molecules with excess diffuse electrons. An unusual class of compounds called electrides comply with these requirements. Many attempts have been made, yet only few electrides have been synthesized as solids and none of them as molecular species. In this paper, a new theoretically designed molecular species with electride characteristics is reported. The idea of this molecular electride comes from the formation of electride-like features in the MgO crystal with defect F-centers. The geometry of the investigated molecule can be described as a Mg O cube with one oxygen atom removed. In Mg O , two 3s electrons are pushed out from the inner area of the molecule forming a diffuse electride multicentered bond. Our calculations show that this electride-like cluster possesses a noticeably large first hyperpolarizability β=5733 au. At the same time, a complete cube Mg O and Mg O without electride electron pair have much smaller β: 0 au and 741 au, respectively. This fact indicates the decisive role of the electride electron pair in NLO properties. Additionally, vertical detachment energies of isomers (VDE), excitation energies ΔE, polarizabilities α, and IR spectra were calculated. These properties, including β, are supposed to be observable experimentally and can serve as indirect evidence of the stable molecular electride formation.
对材料科学的需求不断增长，特别是在非线性光学（NLO）领域，这促使我们寻找具有过剩弥散电子的稳定高极化分子。一类被称为电子化物的化合物就符合这些要求。人们已经做了很多尝试，但只有少数电子化物被合成为固体，而且没有一种是分子态的。本文报道了一种具有电子化物特性的新型理论设计的分子态。这种分子电子化物的想法来源于在具有缺陷 F 中心的 MgO 晶体中形成电子化物样特征。所研究分子的几何形状可以描述为一个带有一个氧原子缺失的 MgO 立方体。在 MgO 中，两个 3s 电子从分子的内部区域被推出，形成一个弥散的电子化物多中心键。我们的计算表明，这个类电子化物簇具有明显较大的第一超极化率β=5733au。同时，完整的 MgO 立方体和没有电子化物电子对的 MgO 的β值要小得多：分别为 0au 和 741au。这一事实表明，电子化物电子对在 NLO 性质中起着决定性的作用。此外，还计算了异构体的垂直离解能（VDE）、激发能ΔE、极化率α和 IR 光谱。这些性质，包括β，预计可以在实验中观察到，并可以作为稳定分子电子化物形成的间接证据。
