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This paper presents the results of computer simulation of tautomeric transformations of the molecule 1-amino-4-phenylamino-9,10-anthraquinone. It is known from the literature that the presence of substituents in the 1,4-position of anthraquinone-9,10 leads to various tautomeric transformations, with a shift in the absorption maximum and the appearance of absorption bands in the red wave region in electronic spectra. Both the 1-amino-4-hydroxyanthraquinone described in the literature and the 1-amino-4-phenylamino-9,10-anthraquinone are characterized by two types of prototropic tautomerism – keto-enol and amino-imine. Quantum-chemical modeling contributes to the calculation of the relative energies of tautomers and isomers, the barriers of their interconversions, as well as finding their structural parameters. The aim of this study was to study the mechanism of the formation of tautomers during hydrogen transfer in the molecule of 1-amino-4-phenylamino-9,10-anthraquinone, as well as the formation of isomers during migration of the OH group. The calculations were performed using the Gaussian09 program. To study of various tautomers of 1-amino-4-phenylamino-9,10-anthraquinone, the B3LYP method with the def2TZV basis was used. A search was conducted for transition states during hydrogen transfer and OH group migration. The descent along the reaction path was calculated to confirm that the transition state is in the path of the desired reaction. The minima corresponding to the starting material and product were localized. The activation enthalpies of the studied reactions were calculated. Migration of the OH group in the 1-amino-4-phenylamino-9,10-anthraquinone molecule leads to the formation of 4-phenylamino-9-amino-1,10-anthraquinone. As the calculation shows, the keto-form of 1-amino-4-phenylamino-9,10-anthraquinone is energetically more profitable than all the isomers studied in this work, including the enol form. The smallest difference in total potential energies is 23.7 kJ/mol between the initial ketone form of 1-amino-4-phenylamino-9,10-anthraquinone and the last transformation structure – the 4-phenylamino-9-amino-1,10-anthraquinone molecule.

This theoretical study was held with purpose to explore fragmentation and isomerization pathways of ethyltoluene radical cation. B3LYP level of theory with 6-31G(d) and 6-311++G(df,p) basis sets was used to calculate potential energy surface of o-, m-, and p-isomers. Single-point energies calculations were carried out using CCSD//B3LYP/6-31G(d). It was found that methyl loss from these seven-membered ring ions requires less energy than either ring methyl loss or direct CH3 detachment from ethyl moiety of ethyltoluene radical cation, which is consistent with previous experimental studies. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

Hydrogenation reaction of ethene on free Ir4 cluster was theoretically investigated using DFT B3LYP level of theory with LanL2Dz basis set. It was found that hydrogen molecule adsorption proceeded without an apparent transition state structure and the adsorption energy was predicted to be −93.7 kJ/mol. Two possible channel of hydrogenation reaction were investigated. Distortion of cluster frame and high values of activation energies make these channels unfavorable. It was shown that inclusion of magnesium oxide (MgO) support model in our calculations account for a considerable variation of geometric parameters of Ir4 cluster. The bonding of a single carbon ligand to the supported tetrahedral Ir4 cluster at the on-top site was also modeled to probe changes in geometric parameters in comparison with unsupported cluster. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

The decomposition of o-, m-, and p-ethyltoluene has been studied by density functional theory. It was found that monomolecular homolytic methyl loss from ethyl moiety seems to be the most favorable mechanism than other proceeding through ethyl, ring-methyl and hydrogen loss. Two possible channels of methane elimination from o-ethyltoluene were studied at B3LYP/6-311++G(df,p) level of theory.

The quantum chemical calculations at the different levels of theory were performed with the target being to determine the vibration frequencies and to estimate the barriers to internal rotations of n-pentane molecules. In connection with the observed losses of CH3 and CH4 from the n-pentane in gas phase, the calculations at the B3LYP level of theory with the 6-31G(d) basis set were used to study the ground-state potential energy surface of the n-pentane. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009

A comparative computational study of the n-butane and the butane cation radical is made by using the B3LYP density functional method with standard basis set 6-31G(d). The conventional transition state theory was used to calculate the enthalpies of butane and its cation radical and the dissociation energies of the CC bond. Basis tendencies in parameter changes of the geometric and electronic structures of molecules and transition states, the enthalpies of formation, and the dissociation energies are analyzed. Computational results are compared with experimental data where possible. On the whole, the B3LYP method exhibits good agreement with experiment. Distinct values of barriers of the similar reactions of molecules and cation radicals are essential. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007