Single and double ionization of corannulene and coronene

Electron-transfer processes that involve single and doubly charged cations of corannulene (C20H10) and coronene (C24H12) are examined by three differe nt mass-spectrometric techniques. Photoionization studies give first-ioniza tion energies of IE(C20H10) = 7.83 +/- 0.02 eV and IE(C24H12) = 7.21 +/- 0. 02 eV. Photoionizations of the neutrals to the doubly charged cations occur at thresholds of 20.1 +/- 0.2 eV and 18.5 +/- 0.2 eV for corannulene and c oronene, respectively. Energy-resolved charge-stripping mass spectrometry y ields kinetic energy deficits of Q(min)(C20H10- = 13.8 +/- 0.3 eV and Q(man )(C24H12 = 12.8 +/- 0.3 eV for the transitions from the mono- to the corres ponding dications in keV collisions. Reactivity studies of the C20H102- and C24H122- dications in a selected-ion flow-tube mass spectrometer are used to determine the onsets for the occurrence of single-electron transfer from several neutral reagents to the dications, affording two different monocat ionic products, With decreasing IEs of the neutral reagents, electron trans fer to doubly charged corannulene is first observed with hexafluorobenzene (IE = 9.91 eV), while neutrals with lower IEs are required in the case of t he coronene dication, e.g. NO2 (IE = 9.75 eV). Density-functional theory is used to support the interpretation of the experimental data. The best esti mates of the ionization energies evaluated are IE(C20H10) = 7.83 +/- 0.02 e V and IE(C24H12) = 7.21 +/- 0.02 eV for the neutral molecules, and IE(C20H1 0) = 12.3 +/- 0.2 eV and IE(C24H12) = 11.3 +/- 0.2 eV for the monocations.