Electronic Spectroscopy of a C7H4+ Isomer in a Neon Matrix: Methyltriacetylene Cation

Abstract

Absorptions commencing at 602.6 nm are detected following deposition of mass-selected C7H4+ in a 6 K neon matrix produced from a 1 : 1 mixture of diacetylene and propyne in an ion source. The 602.6 nm system, and a weaker one near 421.1 nm, are assigned to the A 2E ← X 2E and B 2E ← X 2E electronic transitions of methyltriacetylene cation (C3V symmetry), based on mass-selection, spectroscopic analysis of the vibrational structure, and the excitation energies calculated with CASPT2. Structured fluorescence is detected in the 600–760 nm range upon laser excitation at wavelengths of the CH3C6H+ absorptions. The vibrational bands observed in the absorption and fluorescence spectra are assigned with the aid of calculated frequencies of the totally symmetric (a1) vibrations of methyltriacetylene cation.

Electronic Spectra of Corannulenic Cations and Neutrals in Neon Matrices and Protonated Corannulene in the Gas Phase at 15 K

“…perturbs the energy levels of Cora + . A similar regularity was observed for diacetylene[39] and triacetylene cations[40] substituted with CH 3 , where the origin of the first electronic transition is blue shifted by ≈ 16 and 2 nm, respectively, in comparison to unsubstituted cations. Addition of a hydrogen atom to polyacetylene cations greatly changes the electronic structure.…”

6th Heron Island Conference on Reactive Intermediates and Unusual Molecules

“…pyridine-palladacycles (G. J. Rowlands et al), [5] benzonitrile oxide cycloadditions (G. P. Savage and C. Francis), [6] adamantanethione reactions (N. Drinnan and C. Wentrup), [7] dyesensitised solar cells (E. Brunet et al), [8] iron complexes (P. Comba et al), [9] boric acid catalysed esterification (T. A. Houston et al), [10] amidinium tetrazolide (A. J. Arduengo et al), [11] use of Otera's catalyst (C. A. Hutton et al), [12] methyltriacetylene cation (J. P. Maier et al), [13] retro-Mannich cascade rearrangement (P. Wipf et al), [14] computations on water dimers (E. Kraka et al), [15] cyclopropane radical cation (W. Zou and D. Cremer), [16] nitrile selenides (T. Pasinszki et al), [17] polarization in a halogen bond (T. Clark et al), [18] triazenes (S. Bräse et al), [19] sydnone photochemistry (C. Wentrup et al), [20] dihydroazulene photoswitches (M. B. Nielsen et al), [21] isocyanide-NHC-platinum(II) complexes (A. S. K. Hashmi et al), [22] benzynes (T. Ikawa et al), [23] gold catalysis (A. S. K. Hashmi et al), [24,25] HERON reaction of dialkoxyamides (S. A. Glover et al), [26] silylated enoldiazoacetates (M. P. Doyle et al), [27] and microflow photochemistry (M. Oelgemöller et al). [28] The lively late-afternoon poster sessions on the patio with a view of the sunset and reef sea life (including whales on occasion) are a recurring and unforgettable part of the Heron Island Conferences (Fig.…”