Estimation of the electron affinities of C₆₀, corannulene, and coronene by using the kinetic method

Abstract

Novel anions that contain one molecule each of C 60 and the polycyclic aromatic hydrocarbon coronene are generated in the gas phase by electron attachment desorption chemical ionization. Collision-induced dissociation reveals that these cluster ions are loosely bonded. Fragmentation of the mass-selected cluster anion yields, as the only products, the intact radical anions of the constituent molecules, namely, the C 60 radical anion and the coronene radical anion, in almost identical relative abundances. This result is interpreted as evidence that the cluster ion can be considered as the anion radical of one molecule solvated by the other molecule. The known very high electron affinity of C 60 (2.66 eV) and the comparable degree to which C 60 and the PAH compete for the electron suggests that dissociation may be controlled by the electron affinity of a portion of the C 60 surface, that is, in this case the kinetic method yields information on the "local" electron affinity of C 60 • The electron affinity of the bowl-shaped compound corannulene is estimated for the first time to be 0.50 ± 0.10 eV by the kinetic method by using a variety of reference compounds. Unlike coronene, corannulene reacts with C;.;t in the gas phase to form a covalently bonded, dehydrogenated cluster ion. Support for the concept of "local" electron affinity of C 60 comes from a theoretical calculation on the electronic structure of C 60 anions, which shows evidence for localization of the charge in the C 60 molecule. The possibility of electron tunneling in the C 60-coronene system is discussed as an alternative explanation for the unusual observation of equal abundances of C 60 anions and coronene anions upon dissociation of the corresponding cluster ion.

Negative-ion low-temperature fast-atom bombardment mass spectrometry of monomeric and dimeric [60]fullerene compounds

“…21 but in negative-ion LT-FAB-MS no useful molecular ion peak can be observed with that matrix. In accordance with the high electron affinity of C 60 (2.66 eV 25 ) and with observations made by others, 26 fullerene anions are in general more easily formed than their positive counterparts. This tendency becomes more pronounced for the dimers and, therefore, the FAB matrix should act as solvent and efficient electron donor.…”

Laboratory Infrared Spectroscopy of Gaseous Negatively Charged Polyaromatic Hydrocarbons

“…are well-known to be generally higher than the EAs for the more compact PAHs (Modelli et al 2006), as are the EAs for PAHs comprising one or more five-membered rings (Todorov et al 2008) and fullerenes. The EA for the compact and highly symmetric coronene molecule (C 24 H 12 ) has been established at about 0.5 eV (Betowski et al 2006;Carelli & Gianturco 2012;Chen et al 1996;Denifl et al 2005;Duncan et al 1999;Malloci et al 2005). Although various experimental studies on radical anion PAHs have been reported (Denifl et al 2005;Duncan et al 1999), it is anticipated that these species will be unstable under the conditions of our ESI source and Penning trap due to their low EA.…”

Korbförmige Kohlenwasserstoffe auf Metalloberflächen: Symmetrieunverträglichkeit und Enantiomorphie von Corannulen auf Cu(110)

“…1 kann nicht intakt desorbiert werden, sondern zersetzt sich oberhalb 500 K zu Wasserstoff und Kohlenstoff. Im Einklang mit der geringen Elektronenaffinität von 1 (0.5 eV) [22] [24] -Austauschkorrelationsfunktion der KohnSham-Gleichungen verwendet. Die Wellenfunktionen wurden im Gauß-Basissatz TZVP mit dem Turbomole-Code erweitert.…”