Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5134231 | International Journal of Mass Spectrometry | 2017 | 7 Pages |
â¢Anionic complexes of 1,3,5-trinitrobenzene are characterized in the gas phase.â¢IRMPD spectroscopy points to a covalent Meisenheimer complex structure.â¢Quantum chemical calculations are employed to assign experimental vibrations.â¢Carbon versus oxygen attack by enolate anions is discussed.
Anionic adducts of 1,3,5-trinitrobenzene (TNB) with deprotonated pyrrolidine (Pyr), imidazole (Im), acetone (Ac) and acetylacetone (Acac) have been delivered into the gas phase by electrospray ionization. The so-formed ions, TNB-Nuâ (Nu = Pyr, Im, Ac, Acac), have been interrogated by IRMPD spectroscopy in the fingerprint range. DFT calculations at B3LYP/6-311++G(d,p) level have been performed for a survey of candidate structures. All adducts conform to anionic Ï-complexes (Meisenheimer complexes). The symmetric stretching modes of the nitro groups yield a dominant vibrational signature at 1200-1250 cmâ1, the red-shift with respect to the degenerate frequency of 1367 cmâ1 in neutral TNB reflecting the extent of negative charge delocalization. The enol complexes TNB-Acâ and TNB-Acacâ are largely represented by C-bonded species.
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