M. Yu. Balakina

Ab initio calculation of 14N and 35Cl nuclear quadrupole coupling constants in aziridine and Cl-aziridine

Abstract Ab initio calculations of electric field gradients (EFG) at 14 N and 35 Cl nuclei and conversion to the corresponding nuclear quadrupole coupling constants are reported for aziridine and Cl-aziridine molecules. The structural parameters for Cl-aziridine used for these calculations are obtained as a result of gradient optimization at the HF/4–31G ∗ level. The mutual orientation of the molecular axes and principal axes of the EFG tensor is presented. To evaluate the main contribution from various bonds and lone pairs to the EFG tensor components, a localized molecular orbital (LMO) analysis is made. The comparison of the results of the calculation with experiment is discussed.

Nonempirical calculations of NQR parameters in some three-membered rings

Abstract Ab initio calculations (RHF/6–31G∗) of the electric field gradients (EFGs) at 14N,17O, 2H and 33S and the corresponding nuclear quadrupole coupling constants (NQCCs) are reported for a number of three-membered rings containing atoms of the first and the second rows. The results of the calculations are in good agreement with the available experimental data. The orientations of the principal axes of the EFG tensor at the quadrupole nuclei are determined. The origin of the EFG is analyzed within the framework of the LMO approach. To compare the charge density distributions in aziridine and Cl-aziridine, the charge density maps are obtained using the canonical molecular orbitals.

The effect of chromophores concentration on the nonlinear optical activity of methacrylic copolymers with azochromophores in the side chain

Quadratic nonlinear-optical characteristics of thin films based on methacrylic copolymers with of chromophore-containing monomers incorporated at various concentrations are measured by Second Harmonic Generation technique. Optimal chromophores content is obtained to be about 17 mol%, rather high values of nonlinear-optical coefficient, d33, up to 60 pm/V, are determined.

Ab initio calculations of nitrogen containing free radicals: The geometrical parameters of HFNÖ, H2CNÖ and HFCNÖ radicals

Abstract Geometrical parameters of HFNO, H 2 CNO, ( Z )-HFCNO and ( E )-HFCNO radicals have been calculated by the unrestricted Hartree-Fock metho

ELECTRONIC AND SPATIAL STRUCTURES OF SOME DERIVATIVES OF 5-PHOSPHORANYLIDENBARBITURIC AND 5-PHOSPHORANYLIDENTHIOBARBITURIC ACIDS

AbstractThe spatial and electronic structures of some derivatives of 5-phosphoranylidenbarbituric and 5-phosphoranylidenthiobarbituric acids are investigated within the framework of the semiempirical MNDO approximation. The effect of the substituents at the phosphorus and nitrogen atoms on the geometry and distribution of electron density in the studied molecules is considered. Their pseudoaromatic π-system, which is formed by diffuse lone electron pairs of the

Application of Jamin interferometer for the determination of thin transparent polymer films thickness in the visible range

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Analysis of the hyperfine structure of the EPR spectrum of the radical ions of aryl- and diaryldiazocyanides

ion and two N atoms, involves alternating donor and acceptor centers. The pseudoaromatic fragment in these molecules is nearly planar, and the deviations from planarity are dependent on the size of the substituents at the phosphorus and nitrogen atoms.

Calculating the geometrical parameters of iminoxy radicals using the unrestricted Hartree-Fock-Roothaan method. 2. The radicals Z-HFC=NO. and E-HFC=NO.

On the basis of an analysis of EPR spectra and quantum-chemical calculations, it was shown that a significant change of the hyperfine splitting a31P in phosphoniminoxyls during replacement of alkoxy groups at the phosphorus atom by alkyl groups is mainly governed by electronic factors of substituents at the phosphorus atom.