Comment on: Negative ions, molecular electron affinity and orbital structure of cata‐condensed polycyclic aromatic hydrocarbons by Rustem V. Khatymov, Mars V. Muftakhov and Pavel V. Shchukin

• Published in: Rapid communications in mass spectrometry Vol. 32; no. 3; pp. 230 - 234
• Main Authors: Chen, Edward S., Chen, Edward C.M.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 15.02.2018
• Subjects: Adiabatic flow; Affinity; Anthracene; Beta decay; Electron affinity; Electron capture; Electron capture detectors; Electronegativity; Electrons; Ground state; Molecular structure; Negative ions; Phenanthrene; Polycyclic aromatic hydrocarbons; Spectrometry; Temperature dependence
• ISSN: 0951-4198; 1097-0231; 1097-0231
• DOI: 10.1002/rcm.8021

Rationale The anion mass spectral lifetimes for several aromatic hydrocarbons reported in the subject article were related to significantly different electron affinities. The different values are rationalized using negative ion mass spectral data. Methods Electron affinities for polycyclic aromatic hydrocarbons are reported from the temperature dependence of unpublished electron capture detector data. These are compared with published values and the largest values are assigned to the ground state. Results The ground state adiabatic electron affinities: (eV) pentacene, 1.41 (3); tetracene, 1.058 (5); benz(a)pyrene, 0.82 (4); benz(a) anthracene, 0.69 (2) anthracene, 0.68 (2); and pyrene, 0.59 (1) are used to assign excited state adiabatic electron affinities: (eV) tetracene: 0.88 (4); anthracene 0.53 (1); pyrene, 0.41 (1); benz(a)anthracene, 0.39 (10); chrysene, 0.32 (1); and phenanthrene, 0.12 (2) and ground state adiabatic electron affinities: (eV) dibenz(a,j)anthracene, 0.69 (3); dibenz(a,h)anthracene, 0.68 (3); benz(e)pyrene, 0.60 (3); and picene, 0.59 (3) from experimental data. The lifetime of benz(a)pyrene is predicted to be larger than 150 μs and for benzo(c)phenanthrene and picene about 40 μs, from ground state adiabatic electron affinities. Conclusions The assignments of adiabatic electron affinities of aromatic hydrocarbons determined from electron capture detector and mass spectrometric data to ground and excited states are supported by constant electronegativities. A set of consistent ground state adiabatic electron affinities for 15 polycyclic aromatic hydrocarbons is related to lifetimes from the subject article.