It is common and chemically intuitive to assign cations electrophilic and anions nucleophilic reactivity, respectively. Herein, we demonstrate a striking violation of this concept: The anion [B Cl ] spontaneously binds to the noble gases (Ngs) xenon and krypton at room temperature in a reaction that is typical of "superelectrophilic" dications. [B Cl Ng] adducts, with Ng binding energies of 80 to 100 kJ mol , contain B-Ng bonds with a substantial degree of covalent interaction. The electrophilic nature of the [B Cl ] anion is confirmed spectroscopically by the observation of a blue shift of the CO stretching mode in the IR spectrum of [B Cl CO] and theoretically by investigation of its electronic structure. The orientation of the electric field at the reactive site of [B Cl ] results in an energy barrier for the approach of polar molecules and facilitates the formation of Ng adducts that are not detected with reactive cations such as [C H ] . This introduces the new chemical concept of "dipole-discriminating electrophilic anions."

Alkanes and [B12X12]2− (X = Cl, Br) are both stable compounds which are difficult to functionalize. Here we demonstrate the formation of a boron−carbon bond between these substances in a two-step process. Fragmentation of [B12X12]2− in the gas phase generates highly reactive [B12X11]− ions which spontaneously react with alkanes. The reaction mechanism was investigated using tandem mass spectrometry and gas-phase vibrational spectroscopy combined with electronic structure calculations. [B12X11]− reacts by an electrophilic substitution of a proton in an alkane resulting in a B−C bond formation. The product is a dianionic [B12X11CnH2n+1]2− species, to which H+ is electrostatically bound. High-flux ion soft landing was performed to codeposit [B12X11]− and complex organic molecules (phthalates) in thin layers on surfaces. Molecular structure analysis of the product films revealed that C−H functionalization by [B12X11]− occurred in the presence of other more reactive functional groups. This observation demonstrates the utility of highly reactive fragment ions for selective bond formation processes and may pave the way for the use of gas-phase ion chemistry for the generation of complex molecular structures in the condensed phase.

High-resolution photoelectron spectra of vibrationally pre-excited vinoxide anions (CH 2 CHO − ) are reported using the recently developed IR-cryo-SEVI technique. This method is combined with a newly developed implementation of vibrational perturbation theory that can readily identify relevant anharmonic couplings among nearly degenerate vibrational states. IR-cryo-SEVI spectra are obtained by resonant infrared excitation of vinoxide anions via the fundamental C−O (ν 4 , 1566 cm −1 ) or isolated C−H (ν 3 , 2540 cm −1 ) stretching vibrations prior to photodetachment. Excitation of the ν 4 mode leads to a well-resolved photoelectron spectrum that is in excellent agreement with a harmonic Franck−Condon simulation. Excitation of the higher-energy ν 3 mode results in a more complicated spectrum that requires consideration of the calculated anharmonic resonances in both the anion and the neutral. From this analysis, information about the zeroth-order states that contribute to the nominal ν 3 wave function in the anion is obtained. In the neutral, we observe anharmonic splitting of the ν 3 fundamental into a polyad feature with peaks at 2737(22), 2 835(18), and 2910(12) cm −1 , for which only the center frequency has been previously reported. Overall, 9 of the 12 fundamental frequencies of the vinoxy radical are extracted from the IR-cryo-SEVI and ground-state cryo-SEVI spectra, most of which are consistent with previous measurements. However, we provide a new estimate of the ν 5 (CH 2 scissoring) fundamental frequency at 1395(11) cm −1 and attribute the discrepancy with previously reported values to a Fermi resonance with the 2ν 11 overtone (CH 2 wagging).

The alkylidene double bond configuration of transient ortho-quinone methides (o-QMs) is studied by cryogenic ion trap vibrational spectroscopy.

The molecular ion [B12Cl11]− displays two seemingly incompatible sides, a negative and a positive one, just like the goddess Helja in Norse mythology. Physically, [B12Cl11]− is an anion but it shows chemical reactivity known for highly electrophilic cations. In their Communication on page 7980 ff., S. Grabowsky, J. Warneke et al. report that the electrophilicity of [B12Cl11]− is so high that the noble gases Kr and Xe are bonded spontaneously at room temperature in a reaction that is typical of superelectrophiles.

High-resolution photoelectron spectra of vibrationally pre-excited vinoxide anions (CH2CHO‒) are reported using the recently developed IR-cryo-SEVI technique. This method is combined with a newly developed implementation of vibrational perturbation theory that can readily identify relevant anharmonic couplings among nearly degenerate vibrational states. IR-cryo-SEVI spectra are obtained by resonant infrared excitation of vinoxide anions via the fundamental C-O (𝜈4, 1570 cm−1) or isolated C-H (𝜈3, 2546 cm−1) stretching vibrations prior to photodetachment. Excitation of the 𝜈4 mode leads to a well-resolved photoelectron spectrum that is in excellent agreement with a harmonic Franck-Condon simulation. Excitation of the higher energy 𝜈3 mode results in a more complicated spectrum that requires consideration of the calculated anharmonic resonances in both the anion and neutral. From this analysis, information about the zeroth-order states that contribute to the nominal 𝜈3 wavefunction in the anion is obtained. In the neutral, we observe anharmonic splitting of the 𝜈3 fundamental into a polyad feature with peaks at 2737(22), 2835(18) and 2910(12) cm−1, for which only the center frequency has been previously reported. Overall, nine out of the twelve fundamental frequencies of the vinoxy radical are extracted from the IR-cryo-SEVI and ground state cryo-SEVI spectra, most of which are consistent with previous measurements. However, we provide a new estimate of the 𝜈5 (CH2 scissoring) fundamental frequency at 1395(11) cm−1 and attribute the large difference with previously reported values to a Fermi resonance with the 2𝜈11 overtone (CH2 wagging).

Es entspricht der chemischen Intuition, Kationen elektrophile und Anionen nukleophile Reaktivitätzuzuweisen. Wird emonstrieren hier einen bemerkenswerten Bruchm it diesem Konzept:D as Anion [B 12 Cl 11 ] À bindet die Edelgase (Ngs) Xenon und Krypton spontan bei Raumtemperatur -eine Reaktion, die typisch für" superelektrophile" Dikationen ist. [B 12 Cl 11 Ng] À -Addukte mit Bindungsenergien von 80-100 kJ mol À1 enthalten B-Ng-Bindungen mit erheblichen kovalenten Anteilen. Der elektrophile Charakter des Anions [B 12 Cl 11 ] À wird spektroskopischa nhand der beobachteten Blauverschiebung der CO-Streckschwingung in [B 12 Cl 11 CO] À sowie theoretischm ithilfe von Untersuchungen zur elektroni-schenStruktur nachgewiesen. Die Ausrichtung des elektrischen Felds an der reaktiven Stelle von [B 12 Cl 11 ] À führt zu einer Energiebarriere fürd ie Annäherung von polaren Molekülen und erleichtert die Bildung von Ng-Addukten, die mit reaktiven Kationen wie [C 6 H 5 ] + nicht beobachtet werden. Daher wird das neue chemische Konzept der "Dipol-diskriminierenden elektrophilen Anionen" eingeführt.

Das Ion [B12Cl11]− … …hat Eigenschaften, die nicht vereinbar zu sein scheinen – eine positive und eine negative Seite wie die Göttin Helja aus der altnordischen Mythologie: Physikalisch ist [B12Cl11]− ein Anion, es geht jedoch für stark elektrophile Kationen typische Reaktionen ein. In der Zuschrift auf S. 8090 ff. berichten S. Grabowsky, J. Warneke et al., dass die Elektrophilie von [B12Cl11]− so hoch ist, dass sogar die Edelgase Kr und Xe spontan bei Raumtemperatur gebunden werden – eine typische Reaktion von Superelektrophilen.