Electronic Characterization of Reaction Intermediates: The Fluorenylium, Phenalenylium, and Benz[f]indenylium Cations and Their Radicals

Abstract

Three vibrationally resolved absorption systems commencing at 538, 518, and 392 nm were detected in a 6 K neon matrix after mass-selected deposition of C13 H9 (+) ions (m/z=165) produced from fluorene in a hot-cathode discharge ion source. The benz[f]indenylium (BfI(+) : 538 nm), fluorenylium (FL9(+) : 518 nm), and phenalenylium (PHL(+) : 392 nm) cations are the absorbing molecules. Two electronic systems corresponding to neutral species are apparent at 490 and 546 nm after irradiation of the matrix with λ<260 nm photons and were assigned to the FL9 and BfI radicals, respectively. The strongest peak at 518 nm is the origin of the 2 (1) B2 ←X̃ (1) A1 absorption of FL9(+) , and the 490 nm band is the 2 (2) A2 ←X̃ (2) B1 origin of FL9. The electronic systems commencing at 538 nm and 546 nm were assigned to the 1 (1) A1 ←X̃ (1) A1 and 1 (2) A2 ←X̃ (2) A2 transitions of BfI(+) and BfI. The 392 nm band is the 1 (1) E'←X̃ (1) A1 ' transition of PHL(+). The electronic spectra of C13 H9 (+) /C13 H9 were assigned on the basis of the vertical excitation energies calculated with SAC-CI and MS-CASPT2 methods.

Wöhler‐BASF‐Nachwuchspreis: U.‐P. Apfel / Wheland‐Medaille: J. P. Maier / MacArthur Fellowship: J.‐Q. Yu / Sonderpreis des FCI: H. Maier

“…Maier wurde in dieser Rubrik vorgestellt, als ihm die Erwin‐Schrödinger‐Goldmedaille verliehen worden war . In seiner jüngsten Veröffentlichung in der Angewandten Chemie beschreibt er die elektronische Charakterisierung von Reaktionsintermediaten …”

Stability and Reactivity of the Phenalene and Olympicene Isomers

“…Other PAHs, especially those containing an odd number of carbon atoms, have received much less attention in research. There has been recent progress in calculating the low-lying excited states of the phenalenyl radical and its H-adducts. ,, These investigations shed light on the electronic properties and nature of the excited states of PAH cations, ,,, and anions with an odd number of carbon atoms, including phenalenyl and olympicene anions, have been studied as well, and the differences in the excited state behavior compared to systems with even-number of carbon atoms have been discussed . To the best of the authors’ knowledge, despite significant progress, there remains a gap in the systematic computationally based study on the specific properties, including the excited states, of these promising systems.…”

Revisit on the assignment of electronic spectra of C11H9 +isomers

“…The detailed growth mechanism of PAHs can be determined experimentally by the identification of the isomers of these PAHs cations. The absorption and fluorescence spectra of large number of PAHs cations have been measured with the development of spectroscopic technology [17][18][19][20][21][22][23][24][25][26][27][28][29]. The explanation of these experimental optical spectra is necessary for the identification of polycyclic aromatic isomers.…”