Hydrates and ammonium salts of 4-nitrobenzenesulfonic acid: supramolecular organization and its relation to proton conductivity

Structural features, the crystal packing, and the proton conductivity of a series of hydrates and ammonium salts of 4-nitrobenzenesulfonic acid were studied. It was shown that infinite cation associates containing the onium moiety are responsible for a substantial increase in the proton conductivity. The nature of the disorder in a series of crystals was investigated by performing X-ray diffraction studies at different temperatures. A new type of structural synthons, viz., anion-anion dimers stabilized by the SO₃ ⁻…NO₂ interaction, was found and characterized and the role of solvent water molecules was elucidated based on high-resolution X-ray diffraction data. The water molecules serve mainly as channels for charge transfer from the cation to the anion with retention of the electroneutrality.     

The nature of chemical bonding in nitramide

The spatial and electronic structure studies of nitramide NH₂NO₂ suggest that the change in its molecular geometry upon transition from the gas phase to the condensed state is caused by an increase in the contribution of conjugation between functional groups. According to the analysis of the Bader atomic charges, the effects of such conjugation are to a considerable extent governed by intramolecular charge transfer from the amino to the nitro group. From estimation of the contribution of conjugation to the charge transfer it follows that conjugation remains in the isolated molecule. The influence of hydrogen bonding on the increase in the contribution of conjugation and the corresponding charge redistribution in the molecule was considered. Despite the presence of conjugation between functional groups, the planar configuration of the molecule in the crystal is not realized and the crystallographic twofold axis corresponds to superposition of two molecular configurations with C _s symmetry.     

Bis(4-nitrobenzenethiolato)tetranitrosyldiiron: synthesis,structure, and pharmacological activity of a new nitric oxide (NO) donor

Russian Chemical Bulletin - A preparative procedure was developed for the synthesis of new binuclear tetranitrosyl iron complex of the “μ-S” structural type, [Fe2(SC6H4NO2)2(NO)4]...     

Calculation of thermal conductivity of filled oligomeric compositions

Different models for the calculation of thermal conductivity of oligomeric compositions filled with a dispersed filler (silicon carbide) are studied. It is shown that the calculated values of thermal conductivity of oligomeric compositions with introduced dispersed filler provided by the van Krevelen model developed for the calculation of thermal conductivity of unfilled amorphous polymers with isolated regions of the crystalline phase are the closest to the experimental ones.     

Halogen vs. ionic bonding: an unusual isomorphism between the neutral (C5Me5)2Fe/C2I2 cocrystal and ionic [(C5Me5)2Fe]Br3 crystal

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The influence of the fractional composition of a filler on thermal conductivity of a polymer composition

The dependence of thermal conductivity of polymer composites based on Viksint PK-68 on the dispersion composition of such fillers as powders of silicon carbide and microdiamonds has been studied. It has been shown that the thermal conductivity of polymeric compositions depends on the gradient of fractions in the powders of fillers.     

Charge transfer and hydrogen bond energy in glycinium salts

On the basis of precision X-ray diffraction studies of glycinium trifluoroacetate, glycinium monohydrate with l, 5-naphthalenedisulfonic acid, and the 6h-polymorph of glycine, topological analysis of the electron density distribution function in the crystal was carried out. The sublimation energy of glycine topological analysis of the electron density distribution function in the crystal was carried out. The sublimation energy of glycine was estimated and the role of hydrogen bonds in the charge transfer from the anion to the cation was studied. The role of cation—cation and anion—anion contacts in crystal stabilization was considered. Features of the specific interactions C...C, F...O, and F...N and sulfonic acid SO₃ ^- group were analyzed on the basis of the deformation electron density function and the electron localization function (ELF).