From Neutral Aniline to Aniline Trication: A Computational and Experimental Study

Authors

G. L. Gutsev, Florida A&M University
H. A. López Peña, Virginia Commonwealth University
S. L. McPherson, Virginia Commonwealth University
Derrick Ampadu Boateng, VCU
B. R. Ramachandran, Louisiana Tech University
L. G. Gutsev, Louisiana Tech University
Katharine M. Tibbetts, VCUFollow

Document Type

Article

Original Publication Date

2020

Journal/Book/Conference Title

The Journal of Physical Chemistry A

Volume

124

Issue

16

First Page

3120

Last Page

3134

DOI of Original Publication

10.1021/acs.jpca.0c00686

Comments

This document is the unedited Author's version of a Submitted Work that was subsequently accepted for publication in Journal of Physical Chemistry A, copyright © 2020 American Chemical Society after peer review. To access the final edited and published work see https://doi.org/10.1021/acs.jpca.0c00686

Date of Submission

May 2022

Abstract

We report density functional theory computations and photoionization mass spectrometry measurements of aniline and its positively charged ions. The geometrical structures and properties of the neutral, singly, doubly, and triply positively charged aniline are computed using density functional theory with the generalized gradient approximation. At each charge, there are multiple isomers closely spaced in total energy. Whereas the lowest energy states of both neutral and cation have the same topology C₆H₅–NH₂, the dication and trication have the C₅NH₅–CH₂ topology with the nitrogen atom in the meta and para positions, respectively. We compute the dissociation pathways of all four charge states to NH or NH⁺ and NH₂ or NH₂⁺, depending on the initial charge of the aniline precursor. Dissociation leading to the formation of NH (from the neutral and cation) and NH⁺ (from the dication and trication) proceeds through multiple transition states. On the contrary, the dissociation of NH₂ (from the neutral, cation) and NH₂⁺ (from the dication and trication) is found to proceed without an activation energy barrier. The trication was found to be stable toward abstraction on NH⁺ and NH₂⁺by 0.96 eV and 0.18 eV, respectively, whereas the proton affinity of the trication is substantially higher, 1.98 eV. The mass spectra of aniline were recorded with 1300 nm, 20 fs pulses over the peak intensity range of 1 x 10¹³ W cm^-2 to 3 x 10¹⁴W cm^-2. The analysis of the mass spectra suggests high stability of both dication and trication to fragmentation. The formation of the fragment NH⁺ and NH₂⁺ ions is found to proceed via Coulomb explosion.

Rights

© 2020 American Chemical Society

Is Part Of

VCU Chemistry Publications