The Trifluoromethyl Anion: Evidence for [K(crypt‐222)]<sup>+</sup>

Miloserdov, Fedor M.; Коновалов, А. И.; Martín, Eddy; Benet‐Buchholz, Jordi; Escudero‐Adán, Eduardo C.; Lishchynskyi, Anton; Grushin, Vladimir V.

doi:10.1002/hlca.201700032

Cited by 12 publications

(45 citation statements)

References 45 publications

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“…Our previously published spurious electron density rationale for the residual on the 3‐fold axis receives support from the new DFT data (see below). Nevertheless, a model ( 1‐BE ) was developed with an additional disordered orientation of the

{CF}_{3}^{-}

, like in 1‐MH .…”

Section: Resultssupporting

confidence: 80%

“… The implication was that our assignment of the structure of [K(crypt‐222)] +

{CF}_{3}^{-}

( 1 ) was based exclusively on the crystallographic data. However, as is clear from our reports, 1 was assigned by a combination of X‐ray diffraction, NMR, chemical reactivity, labeling, and computational data. It is ostensibly ‘plausible’ that our sample of 1 was warmed up and diluted with pentane, which resulted in the formation of 2 . In fact, the sample was prepared and maintained at −78 °C in THF as the only solvent throughout the experiment .…”

Section: Resultsmentioning

confidence: 99%

“…An explanation for R 32 being the correct space group for refinements of 1 , 2 , 3 , and BM , as well as details of the updated models for 3 (CCDC 1822623 and 1822624) are presented in the . Although cleaner refinements were obtained for 3 in R 32, the new structure is fundamentally the same as the original one in R 3 …”

Section: Resultsmentioning

confidence: 99%

“…Isomeric [K(crypt‐222)] +

{CF}_{3}^{-}

( 1 ) and [K(crypt‐222{‐H + })]· CHF 3 ( 2 ). Only γ ‐deprotonation is shown as the least disfavored both thermodynamically and kinetically …”

Section: Introductionmentioning

confidence: 99%

“…We also correct some potentially misleading information in the Becker–Müller article . Ultimately and most importantly, we reconfirm our previously drawn conclusions regarding the existence of a ‘naked’ trifluoromethyl anion in a condensed phase.…”

Section: Introductionmentioning

confidence: 99%

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On the Structure of [K(crypt‐222)]⁺

Harlow¹,

Benet‐Buchholz

Miloserdov

et al. 2018

Helvetica Chimica Acta

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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 °C or CD3S(O)CD2K/(D6)DMSO at 23 °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 Müller, 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 Müller's attempts to resolve the charge balance issue have produced models that are inadequate from the perspective of both crystallography and chemistry.

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{CF}_{3}^{-}

, like in 1‐MH .…”

Section: Resultssupporting

confidence: 80%

“… The implication was that our assignment of the structure of [K(crypt‐222)] +

{CF}_{3}^{-}

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…Isomeric [K(crypt‐222)] +

{CF}_{3}^{-}

( 1 ) and [K(crypt‐222{‐H + })]· CHF 3 ( 2 ). Only γ ‐deprotonation is shown as the least disfavored both thermodynamically and kinetically …”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

On the Structure of [K(crypt‐222)]⁺

Harlow¹,

Benet‐Buchholz

Miloserdov

et al. 2018

Helvetica Chimica Acta

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Halogenation and Perfluoroalkylation Chemistry Using Hypervalent Halogen Compounds

Katayev

Jelier

Togni

2018

Patai's Chemistry of Functional Groups

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The introduction of halogenated functional groups by hypervalent iodine(III) reagents has proven to be a popular synthetic method in modern organic chemistry. Such diverse and often unique chemical behavior of iodine(III) compounds originates from their structural and bonding features. In this chapter, we aim to discuss the key structural properties, activation modes, and reactivity trends provided by λ 3 ‐iodane compounds as well as associated challenges therewith. Recent examples of chemo‐, regio‐, and stereoselective iodine(III)‐mediated halogenation and perfluoroalkylation reactions will be presented with an emphasis on contemporary fluorination and trifluoromethylation protocols.

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Counterintuitive deshielding on the ¹³C NMR chemical shift for the trifluoromethyl anion

Viesser

Tormena

2019

Magnetic Reson in Chemistry

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The trifluoromethyl anion (CF 3 − ) displays 13 C NMR chemical shift (175.0 ppm) surprisingly larger than neutral (CHF 3 , 122.2 ppm) and cation (CF 3 + , 150.7 ppm) compounds. This unexpected deshielding effect for a carbanion is investigated by density functional theory calculations and decomposition analyses of the 13 C shielding tensor into localized molecular orbital contributions. The present work determines the shielding mechanisms involved in the observed behaviour of the fluorinated anion species, shedding light on the experimental NMR data and demystify the classical correlation between electron density and NMR chemical shift. The presence of fluorine atoms induces the carbon lone pair to create a paramagnetic shielding on the carbon nucleus.

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The Trifluoromethyl Anion: Evidence for [K(crypt‐222)]⁺

Cited by 12 publications

References 45 publications

On the Structure of [K(crypt‐222)]⁺

On the Structure of [K(crypt‐222)]⁺

Halogenation and Perfluoroalkylation Chemistry Using Hypervalent Halogen Compounds

Counterintuitive deshielding on the ¹³C NMR chemical shift for the trifluoromethyl anion

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The Trifluoromethyl Anion: Evidence for [K(crypt‐222)]+

Cited by 12 publications

References 45 publications

On the Structure of [K(crypt‐222)]+

On the Structure of [K(crypt‐222)]+

Halogenation and Perfluoroalkylation Chemistry Using Hypervalent Halogen Compounds

Counterintuitive deshielding on the 13C NMR chemical shift for the trifluoromethyl anion

Contact Info

Product

Resources

About

The Trifluoromethyl Anion: Evidence for [K(crypt‐222)]⁺

On the Structure of [K(crypt‐222)]⁺

On the Structure of [K(crypt‐222)]⁺

Counterintuitive deshielding on the ¹³C NMR chemical shift for the trifluoromethyl anion