Hydrogen difluoride anion

S. Kawahara et al., Electron correlation and basis set effects on strong hydrogen bond behaviour a case study on the hydrogen difluoride anion. Chem. Phys. 273, 207-216 (2001)... 

Trimethyl(trifluoromcthyl)siIanc is easily fluorodesilylated by tris(dimethyIamino)suIfonium difluorotrimethylsilicate [TASF(Me)], tetrabutylammonium fluoride, or tris(diethylamino) (methylamino)phosphonium hydrogen difluoride and, if arenesiilfonyl fluorides are used to trap the trifluoromethyl anion, trifluoromethyl sulfones are formed in high yield. Trisfdiethyl-amino)(methylamino)phosphonium phenolate is also an effective catalyst for this reaction, but TASF(Me) is favored as it can achieve the quantitative transformation of ArSOjF into aryl trifluoromethyl sulfones. ... 

Miscellaneous.—Hydridofluorophosphates have been prepared for the first time, and the anion (129) has been found to have an octahedral structure, with hydrogens trans.116 Phosphorus pentafluoride forms an adduct with biscyclopentadienyl titanium difluoride.116 The phosphorane (130) has been prepared as shown.117... 

One electron oxidation of silyl enol ether 44 leads to the formation of a radical ion pair of 45 and the xenon difluoride radical anion. Subsequent transfer of a fluoride radical yields cation 46, which reacts by loss of the trimethylsilyl cation to yield the fluoroketone 47. The formation of ketone 49 is explained by a [1,5] -hydrogen migration from the trimethylsilyl group to the radical cationic moiety of 45, leading to the formation of 48. 

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