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Electronic Characterization of Reaction Intermediates: The Fluorenylium, Phenalenylium, and Benz[ f ]indenylium Cations and Their Radicals
Author(s) -
Fulara Jan,
Chakraborty Arghya,
Maier John P.
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201511230
Subject(s) - chemistry , radical , matrix isolation , ion , molecule , neon , molecular electronic transition , absorption spectroscopy , absorption (acoustics) , analytical chemistry (journal) , crystallography , argon , materials science , physics , organic chemistry , chromatography , quantum mechanics , composite material
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 C 13 H 9 + 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 B 2 ←X̃ 1 A 1 absorption of FL9 + , and the 490 nm band is the 2 2 A 2 ←X̃ 2 B 1 origin of FL9. The electronic systems commencing at 538 nm and 546 nm were assigned to the 1 1 A 1 ←X̃ 1 A 1 and 1 2 A 2 ←X̃ 2 A 2 transitions of BfI + and BfI. The 392 nm band is the 1 1 E′←X̃ 1 A 1 ′ transition of PHL + . The electronic spectra of C 13 H 9 + /C 13 H 9 were assigned on the basis of the vertical excitation energies calculated with SAC‐CI and MS‐CASPT2 methods.