On the Structure of [K(crypt-222)]+ CF3-
On the Structure of [K(crypt-222)]+ CF3-
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DOI：
10.1002/hlca.201800015
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发表时间：
2018-04-01
影响因子：
1.8
通讯作者：
Grushin, Vladimir V.
中科院分区：
文献类型：
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作者：
Harlow, Richard L.;Benet-Buchholz, Jordi;Grushin, Vladimir V.
由于无序性，[K(crypt-222)](+) CF3-(1)在晶体学上与它的异构体(去质子化[K(crypt-222)](+), [K（crypt-222{- h +})]CHF3(2)的1:1氟型笼形物）难以区分。在我们之前的出版物中，1是基于x射线衍射，核磁共振，反应性，标记，酸碱和DFT研究的组合来表征的。在这里，我们报告了在CD3OD/CD3OK（70℃）或CD3S(O)CD2K/(D-6)DMSO（23℃）存在的情况下，在数小时甚至数天内，既没有观察到氘的结合，也没有观察到[K(crypt-222)]（+）的任何其他转化。由于氟仿在这种条件下容易且快速地去质子化，因此CHF3相对于[K(crypt-222)]（+）所显示的更大酸度提供了支持1和反对2的额外证据。同样，晶体堆积分析和DFT计算支持1，现在已经在最终正确的空间群R32中进行了改进。我们先前得出的关于[K(crypt-222)](+) cf3和在缩合相中存在裸'三氟甲基阴离子的结论仍然有效。最近的替代改进（Becker和Muller， Chem.）。欧元。J. 2017,23, 7081-7086)的原始衍射数据在错误的空间群中进行了错误的处理，得到了非电荷平衡模型[K(crypt-222)]+CHF3，特此予以否定。Becker和Muller试图解决电荷平衡问题，但从晶体学和化学的角度来看，所产生的模型都是不充分的。
Due to disorder, [K(crypt-222)](+) CF3-(1) is crystallographically indistinguishable from its isomer, a 1:1 fluoroform clathrate of deprotonated [K(crypt-222)](+), [K(crypt-222{-H+})]CHF3 (2). In our preceding publications, 1 was characterized on the basis of combined X-ray diffraction, NMR, reactivity, labeling, acid-base, and DFT studies. Herein we report that neither incorporation of deuterium nor any other transformation of [K(crypt-222)](+) is observed in the presence of CD3OD/CD3OK at 70 degrees C or CD3S(O)CD2K/(D-6)DMSO at 23 degrees C over hours and even days. Since fluoroform is easily and quickly deprotonated under such conditions, the demonstrated greater acidity of CHF3 relative to [K(crypt-222)](+) provides additional evidence in favor of 1 and against 2. Likewise, crystal packing analysis and DFT calculations support 1, which has now been refined in the ultimately correct space group R32. Our previously drawn conclusions regarding [K(crypt-222)](+) CF3-and the existence of a naked' trifluoromethyl anion in a condensed phase remain valid. The recent alternative refinement (Becker and Muller, Chem. Eur. J. 2017, 23, 7081-7086) of our raw diffraction data has been improperly performed in the wrong space group to yield a non-charge-balanced model [K(crypt-222)]+CHF3, which is hereby repudiated. Becker and Muller's attempts to resolve the charge balance issue have produced models that are inadequate from the perspective of both crystallography and chemistry.