VUV photoionization and dissociation of o-nitrotoluene: Experimental and theoretical insights

Conserved Vibrational Coherence in the Ultrafast Rearrangement of 2-Nitrotoluene Radical Cation

“…It is notable that the dispersion-corrected meta-GGA exchange functionals ωB97XD and CAM-B3LYP predict vertical ionization potentials that agree to within 0.05 eV with the recently reported experimental value of 9.43 eV. 21 The neutral, cation, and aci-tautomer geometries are given in the Supporting Information, Figure S3 and Tables S1 and S2. The harmonic vibrational frequencies obtained from these calculations are tabulated in the Supporting Information, Tables S3−S5.…”

“…Previous theoretical studies examined CO loss from only the singlet C 7 H 6 NO + product (P2, Figure 10), which indicated a large 2.61 eV dissociation barrier. 21 We computed the CO loss pathways beginning from the P2 structures in both the singlet and triplet states (Figures 11(a) and (b), respectively, and Supporting Information, Figures S8 and S9). In rough agreement with Ref., 21 the singlet C 7 H 6 NO + requires 2.32 eV to lose the CO moiety.…”

“…The nitrotoluene (NT) isomers 2-, 3-, and 4-NT are often used as model compounds for TNT, and their photodissociation pathways have been studied for decades using mass spectrometric detection of cationic photoproducts. 5,[13][14][15][16][17][18][19][20][21][22] These studies have demonstrated clear differences in reaction pathways of 2-NT as compared to 3-and 4-NT due to the proximity of the CH 3 and NO 2 groups in the 2-nitrotoluyl moiety.…”

“…Upon ionization, all three NT isomers undergo direct homolysis of the weak C−NO 2 bond (Scheme 1), producing the C 7 H + 7 ion with m/z = 91 in mass spectrometry experiments. 5,[15][16][17][18][19][20][21][22] The C−NO 2 cleavage is also the primary initiator of detonation in TNT. The 3-and 4-NT cations also undergo nitro-nitrite rearrangement (NNR, Scheme 2), leading to the loss of NO and the formation of C 7 H 7 O + ions with m/z = 107.…”

“…The aci-nitro tautomer loses OH, forming C 7 H 6 NO + ions with m/z = 120, which can subsequently lose CO to produce C 6 H 6 N + with m/z = 92. 5,13,14,[16][17][18]21 The aci-rearrangement reaction in neutral 2-NT was first reported in 1962 23 and was determined to be the initial step in the sequential dissociation of 2-NT cation to form m/z = 120 and m/z = 92 ions in 1965. 13 More recently, theoretical studies have proposed mechanisms for this sequential dissociation pathway in neutral 2-NT [24][25][26] and 2-NT cation 21 in the gas phase.…”