Synthesis,X-ray analysis,and quantum-chemical DFT study of features in formation of a binuclear phenanthroline complex with a V<Superscript>IV</Superscript>–O–V<Superscript>V</Superscript> core

A new mixed-valence complex [(O)(phen)₂V^IV(μ-O)V^V(O)phen)(mal)]⁺ was synthesized and characterized by the X-ray structural analysis. Its geometric structure was simulated by the DFT M06/6-31G(d,p) method. Comparison of calculated and experimental data made it possible to draw a conclusion on the oxobridging nature of the bond between vanadium fragments and to confirm the value of the target compound charge. The energy characteristics of cation formation reactions in solution were estimated. It was found that the oxidation of V^IV to V^V assists subsequent substitution of ligands. Joining [(O)V^IV(phen)₂]²⁺ and [(O)V^V(O)(phen)(mal)]^– particles proceeds by the donor-acceptor mechanism.     

Catalytic properties of oligonuclear cobalt acetate complexes in oxidation of glutathione with hydrogen peroxide

Catalytic activity of oligonuclear cobalt(III) and cobalt(II, III) oxoacetate complexes in homogeneous oxidation of glutathione with hydrogen peroxide was studied.     

Synthesis,crystal and molecular structures of the octanuclear cationic mixed-valence cobalt acetate complex

A new octanuclear mixed-valence cobalt acetate complex of the cationic type [Co₄ ^IICo₄ ^III(μ₄-O)₄(μ₃-OMe)₄(μ-OAc)₆(H₂O)₈]F₂ · 10H₂O ([I]F₂ · 10H₂O) was prepared by crystallization from a solution of ‘cobalt(III) acetate’ in a Me₂CO-MeOH-H₂O-HF mixture and studied by X-ray diffraction. The crystals are monoclinic: space group C2/c, a = 17.222 Å, b = 16.836 Å, c = 16.586 Å, β = 94.902°, Z = 4, R = 4.37% (I > 2σ(I)). In the crystal, the I²⁺ complex cations, fluoride anions, and solvate water molecules form a three-dimensional (3D) coordination supermolecular system.     

Features of the Formation of the [(O)VIV(C2O4)(Phen)(H2O)] Complex in the Malic Acid Oxidation Process

Complex [(O)V^IV(C₂O₄)(Phen)(H₂O)] was obtained on the basis of V₂O₅ and malic acid in the presence of concentrated HNO₃ and phenanthroline. Its structure was determined by the X-ray structural analysis; its magnetic susceptibility was measured. The role of the \(\rm{VO}^+_2\) and VO²⁺ cations in the oxidation and complex-formation processes was considered. A method for the conversion of malic acid to oxalate anions through the formation of oxaloacetic acid and the intermediate products of its decarboxylation reactions was proposed. It was shown by the DFT M06/6-31G(d,p) method that the transition state energy decreases in the way of the HOC(O)C(0)CH₂-COOH bond breakage during decarboxylation compared with the free acid in the intermediate of its anion with VO²⁺.

     

Protolytic equilibria of picric acid in a mixture of protophobic and protophilic polar solvents non-donors of H-bonds

A new differentiating medium for the study of prototropic equilibria is proposed: acetonitrile with a small addition of DMSO. From the dependence of the picric acid pK _a on the content of DMSO in this medium the optimum composition of the mixture was found ensuring the stability of the pK _a values with minimal addition of DSMO: 4 wt %. It was experimentally confirmed that the addition of water in an amount up to 0.1 wt % has virtually no effect on the measured pK _a value in a mixture with the optimum composition.     

High-rate combustion of cellulose nitrate in filled polymer systems

It was found that, at a certain external pressure, the conventional slow flameless combustion of nitrocellulose in filled compositions can go over into a high-rate low-temperature mode, with a burning velocity increasing by more than 40-fold. It was shown that the critical external pressure at which the changeover of the combustion modes occurs decreases with the sample porosity. It was assumed that the high-rate combustion of nitrocellulose in filled systems proceeds by the well-known mechanism of convective combustion of energetic condensed systems with some specific features.     

Experimental testing of the calculation results of the dissociation constants of organic compounds in nonaqueous media

27 Dissociation constants of carboxylic and NH-acids in methanol, ethanol and formamide were measured by potentiometric method. The selection of compounds for the analysis is determined by the preliminary computation of the constants by elemental linear empirical method, and also by the absence of the consistent published data on the values for the chosen compounds. The comparison of results showed that the obtained values of dissociation constants as a rule are consistent with those predicted in the range with the relative error of 10%.