Phenanthrene: establishing lower and upper bounds to the binding energy of a very weakly bound anion

Abstract

Collisional excitation of CaPh−, formed in helium nanodroplets, produces Ca− but no phenanthrene anions. We conclude that the EA of Ph is below that of Ca, i.e. below 24.55 meV.

Stabilization of phenanthrene anions in helium nanodroplets

“…below 24.55 meV. 32 In this contribution, first, we confirm by performing electron attachment measurements that Ph À is not observed isolated in the gas phase, and secondly, we show that bare Ph À can be stabilized in the HND environment by a suitable choice of parameters, albeit in very small amounts. Nonetheless, from these results we conclude, that Ph has a small, but positive EA.…”

“…Only He n Ph − (7 ≥ n > 0) fragments, but no bare Ph − were detected. 32 The “non-detection” of the bare anion might be explainable by the higher transferred collision energy of Ar atoms in comparison to He atoms. Moreover, the measurements were aggravated by larger noise/poorer counting statistics.…”

“…Recently, our group studied complexes of Ph with various ligands M with negative (He, H 2 , H 2 O) or extremely small EA (Ca, EA = 24.55 meV) embedded in helium nanodroplets (HNDs). 32 We showed that long-lived He n Ph À are formed in HNDs and fragment by low-energy collisions with Ar atoms into He n Ph À with n 4 0. Bare Ph À was not observed.…”

Electrospray-Ionization Mass Spectrometry for the Analysis and Quantification of Carbanions

“…55 Other research focused on the proton affinity of anions 56 or affinities of neutral molecules towards alkali metal cations. 57 For inversed charges, bridging small anions like halides 58 or electrons 59 have been investigated, the latter being another way to determine electron affinities.…”

“…Defined for the gas-phase electron attachment reaction, this thermodynamic parameter can sometimes be determined by the kinetic method as described in chapter 1.2.5. 59 Other methods include various forms of spectroscopy upon the attachment 74 or emission 75 of an electron and similar measurements based directly on that reaction. 76 Among the most reactive species commonly utilized in synthetic chemistry are lithium organyls, featuring extreme basicity.…”