NMR spectra of arylaziridines

The ¹³C and ¹H NMR spectra of 1-arylaziridines, 2-phenyl-1-arylaziridines, and 2-aryl-1-phenylaziridines were studied. The additive contributions of aziridinyl, 1-phenyl-2-aziridinyl, and 2-phenyl-1-aziridinyl substituents to the shielding of the aromatic protons were calculated. It is shown that with respect to its donor capacity the aziridine ring occupies an intermediate position between amines and amides. The temperature dependences of the PMR spectra of 1-aryl-substituted aziridines were investigated, and the barriers to inversion of the latter were calculated. The dependence of G on the ^– constants was correlated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 338–341, March, 1978.     

Calculation of boltzmann equation collision integral and accurate solution of relaxation problem

A method of solving the Boltzmann equation on the basis of expansion in Maxwell distributions (Maxwellians) is developed. The calculation of the collision integral consists of two stages: calculation of a two-Maxwellian collision integral and its subsequent expansion in Maxwellians. A special numerical procedure is proposed for approximating functions of one and two variables by a finite number of exponentials; the mean-square deviation of the accurate and approximate functions is minimized and certain moments of these functions are brought into agreement. For a solid-sphere model, the two-Maxwellian collision integral comprises a set of 24 functions over the whole range of the parameters investigated. The Euler method is used to examine the equalization of velocities and temperatures in the gas (quasishock) and resonance recharging of ions on atoms. The accuracy of the solutions obtained is estimated.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 132–141, September–October, 1977.     

Reactions of 2,2-dimethyl-3-phenylazirine with hydrazine and its derivatives

The corresponding -amino ketone hydrazones were obtained by reaction of 2,2-dimethyl-3-phenylazirine with hydrazine, N,N-dimethylhydrazine, methylhydrazine, and semicarbazide. It was established that unsymmetrical azines are formed in the reaction of 2-amino-2-methyl-1-phenyl-1-propanone hydrazone with aliphatic and cyclic ketones. The corresponding tetrahydro-1,2,4-triazines were obtained in the case of the analogous reaction with aliphatic and aromatic aldehydes.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 342–346, March, 1978.     

Correlations and accuracy of estimation of spectroscopic constants and term values

A comparison and evaluation of the various methods for reducing spectroscopic data to spectroscopic constants or term values is made with the aid of an analysis of a number of “synthetic” Σ-Σ bands generated from fixed sets of constants with random noise superimposed on the line positions. It is shown that the strong correlations that exist between the upper-state constants B′, D′ and the lower-state constants B₀, D₀ can be effectively broken up by using the difference constants ΔB = B′ - B₀ and ΔD = D′ - D₀, along with ν₀, for representing the upper states. The lower state constants B₀ and D₀ and their standard errors calculated from the combination differences Δ₂F″(J) are shown to be as good as those obtained from direct polynomial fits. If data for a number of bands originating in the same lower state are available, a considerable increase in accuracy of estimating the lower-state constants can be attained by analyzing the bands simultaneously, e.g., using combination differences, provided the data are free from systematic errors. The dependence of the accuracy of determining the constants B₀, D₀, ν₀, ΔB, and ΔD on the extent of the band analyzed was investigated by varying the minimum and maximum J-values. The plots showing this dependence for both the actual errors and standard errors can be used e.g., to assess the band size necessary to attain a desired accuracy for a given constant.Åslund's term-value method is cast in a form which permits simple derivation of explicit formulas for the correlation coefficients connecting all the upper- and lower-state term values, and of explicit relations between the term values and the combination differences. Modifications of the term-value method suitable for the case where one or more transitions originate in an unperturbed state are explored. It is shown that the “difference term values” referred to the lower (unperturbed) state with the same value of J, T_i(J)-T₀(J), are essentially uncorrelated to the lower state constants B₀ and D₀. Since these quantities can be expressed directly as the eigenvalues of the energy matrix for a given J in the presence of perturbations, their use for representing the energies of perturbed rovibronic states is recommended.     

Inclusion complexing by water-soluble β-cyclodextrin polymers

Cross-linked -cyclodextrin with a molecular weight of less than 10000 has good solubility in water, and it is a better inclusion complexing agent than the parent -cyclodextrin. By including lipophilic guest molecules into the apolar cyclodextrin cavity, their apparent lipophilicity is reduced because the outer surface of the molecular wrapping (the crosslinked -CD) is highly hydrophilic. The relative stability of the inclusion complexes can be rapidly determined by reversed-phase thin-layer chromatography. The reversed-phase TLC behaviour of 25 triphenylmethane derivatives and analogues were studied in the presence of -cyclodextrin polymers containing neutral and carboxyl groups. Increasing the molecular weight results in an increased complex-forming capacity. The carboxyl group modifies the accessibility of the CD cavity which in turn results in increased or decreased complex stability, depending on the guest molecule. The presence of organic solvents diminishes the stability of the CD complexes.     

Effect of σ,π conjugation on199Hg chemical shifts

Conclusions The¹⁹⁹Hg NMR spectra of compounds of the type HgCC=C and HgCC=0 have been studied and it has been shown that C-Hg/ conjugation produces a sharp increase in the shielding of the mercury nucleus.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1038–1042, May, 1982.