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Quantum-chemical interpretation of cyclization and recyclization reactions. 27. Electrocyclization of phenyl derivatives and benzoannelated derivatives of 1,2,4-triazahexa-1,3,5-triene and 1,2,4-oxadiazahexa-1,3,5-triene

“…As also in the case of polyenes [21,22], P 0 ik (0) of remote bond orders in compounds 1-3 assume larger positive values only for those pairs of atoms which correspond to the formation of six-membered rings (Table 1). For example, for 1,4-diphenyl-1,2,4-triazabutadiene (1c) P 1,2a (0) = 0.1125, P 4,2b (0) = 0.1101.…”

“…We stress that with the parametrization used previously electrical, diamagnetic, and spectral characteristics have been calculated for a series of five-and six-membered heterocycles (see for example [20]), thermal rearrangements have been described for a series of annelated hexatrienes and polyenes [21,22], a quantum-chemical interpretation has been given for the Kost-Sagitullin [23,24] and Elbs [25,26] reactions, etc.…”

“…We note that substituents in the benzene ring of the quinoline fragment have practically no effect on the remote bond orders P 4,2b and P 1c,2b . Since the remote bond orders characterize the height of the potential barrier to cyclization [16,21,22], then it is pertinent to use them as indexes of reactivity on kinetic control of the reaction. In the same case, when the barrier to reaction is low, a determining role in the choice of the main reaction pathway is played by the energy characteristics of the products.…”

Superposition-additive approach in the description of thermodynamic parameters of formation and clusterization of substituted alkanes at the air/water interface

“…This method developed by the authors earlier is referred to as the superposition-additive approach [2][3][4][5], because it involves the superposition principle and assumes the additivity of atomic properties in molecules.…”

“…One of the applications based on this postulate is the superposition-additive approach developed earlier by one of the authors. This approach was initially proposed and verified for the description of the electronic structure of the oxazole cation [2] and was subsequently applied for the calculations of the electronic structure and physicochemical properties of conjugate systems [3,4]. The charges and bond orders in carbenes were determined using this approach [5].…”