Matsumoto Kazuhiko, Haruki Yuki, Sawada Shunsuke, Yamada Shigeyuki, Konno Tsutomu, Hagiwara Rika
Graduate School of Energy Science , Kyoto University , Yoshida, Sakyo-ku, Kyoto , 606-8501 , Japan.
Faculty of Molecular Chemistry and Engineering , Kyoto Institute of Technology , Matsugasaki, Sakyo-ku, Kyoto , 606-8585 , Japan.
Inorg Chem. 2018 Dec 3;57(23):14882-14889. doi: 10.1021/acs.inorgchem.8b02655. Epub 2018 Nov 16.
The stabilization of complex fluoroanions derived from weakly acidic parent fluorides is a significant and ongoing challenge. The [SF] anion is recognized as one such case, and only a limited number of [SF] salts are known to be stable at room temperature. In the present study, glyme-coordinated alkali metal cations (K, Rb, and Cs) are employed to stabilize [SF], which provides a simple synthetic route to a [SF] salt. The reactivities of KF and RbF with SF are significantly enhanced by complexation with G4, based on Raman spectroscopic analyses. A new room-temperature stable salt, [Cs(G4)][SF] (G4 = tetraglyme), was synthesized by stoichiometric reaction of CsF, G4, and SF. The vibrational frequencies of [SF] were assigned based on quantum chemical calculations, and the shift of the G4 breathing mode accompanying coordination to metal cations was confirmed by Raman spectroscopy. Single-crystal X-ray diffraction revealed that Cs is completely isolated from [SF] by two G4 ligands and [SF] is disordered along the crystallographic two-fold axis. Hirshfeld surface analysis reveals that the H···H interaction between two neighboring [Cs(G4)] moieties is more dominant on the Hirshfeld surface than the interaction between the H atom in glyme molecules and the F atom in [SF], providing a CsCl-type structural model where the large and spherical [Cs(G4)] cations contact each other and the [SF] anions occupy interstitial spaces in the crystal lattice. The [SF] anion, combined with [Cs(G4)], exhibits a very limited deoxofluorinating ability toward hydroxyl groups in both neat conditions and THF solutions.
由弱酸性母体氟化物衍生而来的复合氟阴离子的稳定化是一项重大且仍在持续的挑战。[SF]阴离子就是这样一个例子，已知只有少数[SF]盐在室温下是稳定的。在本研究中，使用乙二醇二甲醚配位的碱金属阳离子（K、Rb和Cs）来稳定[SF]，这为合成[SF]盐提供了一条简单的路线。基于拉曼光谱分析，KF和RbF与SF的反应活性通过与G4络合而显著增强。通过CsF、G4和SF的化学计量反应合成了一种新的室温稳定盐[Cs(G4)][SF]（G4 = 四甘醇二甲醚）。基于量子化学计算确定了[SF]的振动频率，并通过拉曼光谱证实了G4呼吸模式随与金属阳离子配位的位移。单晶X射线衍射表明，Cs通过两个G4配体与[SF]完全隔离，并且[SF]沿晶体学二重轴无序排列。Hirshfeld表面分析表明，两个相邻[Cs(G4)]部分之间的H···H相互作用在Hirshfeld表面上比甘醇二甲醚分子中的H原子与[SF]中的F原子之间的相互作用更占主导地位，提供了一种CsCl型结构模型，其中大的球形[Cs(G4)]阳离子相互接触，[SF]阴离子占据晶格中的间隙空间。[SF]阴离子与[Cs(G4)]结合，在纯态条件和THF溶液中对羟基均表现出非常有限的脱氧氟化能力。
