The Trifluoromethyl Anion

Abstract

First evidence for the existence of free trifluoromethyl anion CF 3 À has been obtained. The 3D-caged potassium cation in [K(crypt-222)] + is inaccessible to CF 3 À ,t hus rendering it uncoordinated ("naked"). Ionic [K(crypt-222)] + CF 3 À has been characterized by single-crystal X-rayd iffraction, solution NMR spectroscopy, DFT calculations,a nd reactivity towarde lectrophiles.

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

“…This disorder, which is intrinsic to the nature of the compound in the solid state, did not allow us to unambiguously formulate the solid as [K(crypt‐222)] + on the basis of the crystallographic results alone. Therefore, in our report we indicated that the X‐ray data could also account for a highly improbable 1:1 clathrate of CHF 3 with deprotonated [K(crypt‐222)] + ( 2 ; Fig. ) …”

“…As crystal re‐growth was clearly not an option for 1 , a different approach to probe the crystallographically was sought. We proposed that determining the structure of a [K(crypt‐222)] + salt that is compositionally akin to 1 might serve our purpose in a way that resembles the use of independent synthesis for structure elucidation in organic chemistry.…”

“…The crystal structure of [K(crypt‐222)] + ( Fig. ) represents a particularly interesting and important case study. Our X‐ray analysis of crystals produced upon treatment of t BuOK/crypt‐222 with i Pr 3 SiCF 3 (TIPSCF 3 ) in THF at −78 °C suggested ionic [K(crypt‐222)] + .…”

“…) represents a particularly interesting and important case study. Our X‐ray analysis of crystals produced upon treatment of t BuOK/crypt‐222 with i Pr 3 SiCF 3 (TIPSCF 3 ) in THF at −78 °C suggested ionic [K(crypt‐222)] + . The collected data for the extremely challenging sample were of excellent quality, except for the relatively low data to parameter ratio due to a high level of disorder in the crystal.…”

“… ORTEP drawing of [K(crypt‐222)] + ( 1 ) with thermal ellipsoids drawn at the 50% probability level …”