A. A. Korlyukov

Chemical bonding in isolated molecules and crystals of zwitterionic pentacoordinate silicon chelates

The electronic structures of a number of zwitterionic pentacoordinate silicon chelates were investigated using the results of X-ray diffraction studies and quantum-chemical calculatoins by the MPW1PW91/6-311G(d) method. The topological analysis of the electron density distribution function and the study in the framework of the natural bond orbital partitioning scheme showed that the character of chemical bonding in the axial fragments of the molecules under consideration changes from dative to three-center, four-electron as the silicon atom assumes a trigonal-bipyramidal coordination.

Electrophilic Substitution in the Dihydroquercitin System. Aminomethylation

Treating dihydroquercetin with formaldehyde and amines under conditions of Mannich reaction provided mono- and diaminomethyl derivatives of dihydroquercetin.

The relative strength and role in crystal packing of I−⋯π and CH⋯I− interactions in iminium salts

The relative energy and importance of Hal−⋯π and CH⋯Hal− interactions were studied basing on the crystal structures of iminium salts with different I⋯C distances. DFT calculations of the corresponding cations and ionic pairs were performed in an isolated state, accompanied by PW-DFT calculations of the crystals. The QTAIM methods in conjunction with the Espinosa–Lecomte correlation scheme were used to estimate the energies of C⋯I and H⋯I interactions both in isolated and in solid state. A detailed CSD survey was performed to estimate the relative abundance of these interactions in iminium salts.

Synthesis and structures of tris(pentafluorophenyl)silylamines

Tris(pentafluorophenyl)silylamines were synthesized by silylation of amines and imines with (C6F5)3SiCl or (C6F5)3SiOTf in the presence of triethylamine. The crystal structures of the (C6F5)3SiN(H)CH2Ph and (C6F5)3SiN(CH=CMe2)CH2Ph compounds were studied by X-ray diffraction. The crystal packings were analyzed by quantum chemical calculations in terms of the density functional theory (PBE exchange-correlation functional).

X-ray diffraction and quantum-chemical study of 3-(1,3-dioxolan-2-yl)-4,6-dinitrobenzo[d]isoxazole

X-ray diffraction study of the molecular structure of 3-(1,3-dioxolan-2-yl)-4,6-dinitrobenzo[d]isoxazole in the crystal, and quantum-chemical calculations of the isolated molecule demonstrated that the differences in the reactivity of the nitro groups at positions 4 and 6 are not associated with the electronic structure of the molecule but are, apparently, attributed to the properties of the corresponding ipso-σ complexes.

Synthesis and the structure of tribromo(7-bromobicyclo[4.1.0]hept-7-yl)germane

A general procedure was developed for the synthesis of halocyclopropylgermanes. This procedure was used for the preparation of tribromo(7-bromobicyclo[4.1.0]hept-7-yl)germane. The molecular structure was established by GLC-mass spectrometry, 1H NMR spectroscopy, and X-ray diffraction analysis.

New disiloxane based on N-acetylvaline: synthesis and structure

Silylmethylation of N-acetylvaline with the ClCH2SiMe2Cl—(Me3Si)2NH system gave the previously unknown 2-silamorpholin-6-one derivative, whose hydrolysis in aqueous ethanol produced bis-acetylvaline-containing disiloxane. The X-ray diffraction study and quantum chemical calculations demonstrated that both silicon atoms in the final product are four-coordinated.

Synthesis and structural features of new pentacoordinated monofluorosilanes containing C,O-chelate ligands based on 2-amino acid N-methylamides

Pentacoordinated monofluorosilanes R1SO2NHCHR2C(O)N(Me)CH2SiMe2F containing moieties of N′-methyl-N-(organosulfonyl)-2-amino acid amides of glycine, alanine, and leucine as C,O-chelating ligands were synthesized via the reaction of corresponding disiloxanes with BF3•Et2O. The structures of obtained compounds were investigated by single-crystal X-ray diffraction analysis.

Lactamomethyl derivatives of diphenols: synthesis, structure, and potential biological activity

A series of mono-, bis-, and tris-substituted lactamomethyl derivatives of diphenols were synthesized. The solution and solid-state structures of these compounds were confirmed by IR and NMR spectroscopy and X-ray diffraction. The in silico evaluation indicated a high probability that these compounds have various biological activities.

Analysis of strong and weak inter- and intramolecular interactions in the crystals of carborane derivatives

Organic compounds exhibiting photoor thermochromicity are of considerable interest owing to their properties and possible applications. The photochromism of salicylideneaniline (SA) was discovered by Senier et al. at the beginning of last century, and in 1964, Cohen et al. [1] observed its polymorphism. It is generally accepted that the stable form of SA in the ground state is the enol form, with an intramolecular hydrogen bond between the hydroxyl proton and the nitrogen atom. Upon photoexcitation of this enol form with UV light, it undergoes an ultrafast proton transfer from the hydroxyl group to the nitrogen, due to the electronic redistribution in the excited state. The proton transfer generates a keto tautomer in the excited state. We report on the alpha-2-polymorph structure of SA in the ground state [2].We also describe a new polymorph, beta, which features a planar SA molecule and is therefore thermochromic. We did also revisit the alpha-1-polymorph structure of SA described by Destro et al. [3], but reconsidering their hypothesis. We suggest a lowering of the symmetry with the aim to improve the structure solution.