Electronic descriptors for analytical use of the benzidine‐based compounds and the mechanism of oxidative coupling of anilines

Abstract

A number of hybrid exchange-correlation functionals, namely, B3LYP, BMK, M06-2X, PBE0, CAM-B3LYP, BH&HLYP, and HSE06, have been employed to calculate the electronic spectra of a series of the N,N′-derivatives of benzidine, their radical cations, and dications; the results are compared with available experimental data. In most cases studied, the timedependent density functional theory results based on the CAM-B3LYP and BMK functionals indicate a better agreement with the experimental absorption bands in the UV-Vis spectra. The other five functionals provide statistically comparable but lower accuracy. On the basis of the time-dependent density functional theory calculations with both the CAM-B3LYP and BMK functionals and the 6-311 + G(d,p) basis set including effect of polar medium simulation, the electronic spectrum of the benzidine dication has been completely assigned. Because the latter dication is formed during oxidative coupling of two aniline molecules, as the reductive reagents for analytical determination of strong oxidants, the mechanism of this reaction has been clarified on the ground of density functional theory calculations including effect of dispersion for all possible reaction paths and intermediates. By the analysis of spectral properties and ionization energies of several aniline derivatives, a few simple electronic descriptors that help to justify a reagent molecule as a potentially favorable for colorimetric use have been proposed.

Formation of persistent organic diradicals from N,N′-diphenyl-3,7-diazacyclooctanes

“…This mechanism is in line with one discussed by Bondarchuk and Minaev for the oxidative coupling of anilines [29]. More generally, it is related to the oxidative dimerization of arylamines to benzidines with Cu 2+ or iron oxidants [22, 30, 31].…”

Spontaneous disproportionation of lithium biphenyl in solution: a combined experimental and theoretical study

“…Note that the resonance structure of the Bph 2is the same as for the previously calculated biphenyl and benzidine dication. 27,28 The QTAIM properties of these contact ionic pair are listed in Table S5 in ESI. Calculations of the electronic spectra of the aforementioned associates are illustrated in Fig.…”

A combined experimental and density functional study of 1-(arylsulfonyl)-2-R-4-chloro-2-butenes reactivity towards the allylic chlorine

“…Recently, we have found that a number of local Quantum Theory of Atoms in Molecules properties are convenient for the structure‐activity description in benzidine and its singly and doubly oxidized forms . Being calculated in the bond critical points (BCP), these can clarify the electron distribution and, consequently, the reactivity.…”

“…Recently, we have found that a number of local Quantum Theory of Atoms in Molecules properties are convenient for the structure-activity description in benzidine and its singly and doubly oxidized forms. [49,50] Being calculated in the bond critical points (BCP), these can clarify the electron distribution and, consequently, the reactivity. Among these AIM quantities, we have used the electron density ρ(r), its Laplacian ∇ 2 ρ(r), energy densities h e (r), g(r), and v(r), [51] bond ellipticity ε(r), [51] average local ionization energy Ī(r), [52] localized orbital locator, [53] and electron localization function (ELF).…”