V. Yu. Korotaev

Stability of the Mo72Fe30 polyoxometalate buckyball in solution

The stability of the [Mo72Fe30O252(CH3COO)12{Mo2O7(H2O)}2{H2Mo2O8(H2O)}(H2O)91] · ∼150H2O polyoxometalate (Mo72Fe30) with a buckyball framework structure in solution has been investigated as a function of the solute concentration, illuminance, the presence/absence of a polymer, and the acidity of the medium. The polyoxometalate ions can form association species with molecules of water-soluble nonionic polymers, such as polyvinyl alcohol and polyvinylpyrrolidone. Electrotransport properties of the polyoxometalate ions—mobility, transport number, and diffusion coefficient—have been measured. The catalytic activity and stability of Mo72Fe30 in a redox reaction have been evaluated.

Reactions of 3-nitro-2-trihalomethyl-2H-chromenes with S- and N-nucleophiles. Synthesis and stereochemistry of 2,3,4-trisubstituted chromanes

The reactions of 3-nitro-2-trifluoromethyl-and 3-nitro-2-trichloromethyl-2H-chromenes with thiols and aromatic amines proceed via the nucleophilic addition type to the activated double bond to form 2,3,4-trisubstituted chromanes in high yields. The stereoisomeric compositions and structures of the diastereomers were determined by 1H, 19F NMR and 2D NOESY spectroscopies and X-ray diffraction analysis.

Reactions of 3-nitro-2-trihalomethyl-2H-chromenes with C-nucleophiles. Synthesis of 3-nitro-4-(pyrazol-4-yl)-2-trihalomethylchromanes

The nucleophilic addition of acetylacetone and ethyl acetoacetate at the double bond of 3-nitro-2-trihalomethyl-2H-chromenes in the presence of NaH affords 2,3,4-trisubstituted chromanes containing the β-dicarbonyl fragment at position 4. The trans-trans configuration and the enol structure of the reaction products were confirmed by 1H NMR spectroscopy and X-ray diffraction. Treatment of these compounds with hydrazine gives the corresponding 3-nitro-4-(pyrazol-4-yl)-2-trihalomethylchromanes. The reactions of 3-nitro-2-trihalomethyl-2H-chromenes with nitromethane and nitroethane in the presence of K2CO3 produce 1,3-dinitro derivatives of the chromane series.

Thermal behavior of polyoxometalate Mo132

Thermal destruction of (NH4)42[Mo72VIMo60VO372(H3CCOO)30(H2O)72]30H3CCOONH4 · 250H2O, polyoxometalate Mo132, was analyzed. Differential scanning calorimetry (DSC) and mass spectrometry were investigative tools. Thermal destruction occurs in air and in nitrogen in three main stages. First, water is eliminated. The thermolysis products at higher temperatures include acetamide and acetonitrile. Molybdenum oxides are formed in solid products through an amorphous stage. The utility of NMR spectroscopy for analyzing poly(oxometalates) is demonstrated.

Reactions of 3-nitro-2-trihalomethyl-2H-chromenes with indole, N-methylindole, and N-methylpyrrole. Stereoselective synthesis of 4-azolyl-3-nitro-2-trihalomethylchromanes

Heating of 3-nitro-2-trifluoromethyl-and 3-nitro-2-trichloromethyl-2H-chromenes with indole, N-methylindole, and N-methylpyrrole under solvent-free conditions led with high stereoselectivity and in good yields to cis-trans-3-nitro-2-trifluoromethyl-or trans-cis-3-nitro-2-trichloromethylchromanes substituted by the indol-3-yl (pyrrol-2-yl) fragment in position 4.

Study of the stability of solid polyoxometalate Mo72Fe30 with a buckyball structure

Samples of polyoxometalate Mo72Fe30: [Mo72Fe30O252(CH3COO)12{Mo2O7(H2O)}2 {H2Mo2O8(H2O)}(H2O)91] · ≈150H2O with a buckyball structure, which can be both crystalline and amorphous, were synthesized. It was shown that such samples can be studied by neutron diffraction. The stability of Mo72Fe30 to heating and UV light exposure (in poly(vinyl alcohol) and polyvinylpyrrolidone films) was studied by IR, EPR, and electronic absorption spectroscopy; thermal analysis; and mass spectrometry. Mo72Fe30 was found to be less stable to heating and irradiation in a poly(vinyl alcohol) film as compared with the related polyoxometallate Mo132 free of iron. The sorption properties of Mo72Fe30 to organic vapors and its stability under sorption conditions were studied. It was demonstrated that, in addition to sorption, organic substances cause the destruction of buckyballs.

Spectroscopic studies of molybdenum polyoxometallates with the buckyball structure and polymer-containing compositions based thereon

Molybdenum polyoxometallates with the buckyball structure, ((NH4)42[Mo72VIMo60VO372(H3CCOO)30(H2O)72] · 30H3CCOONH4 · 250H2O (I), (NH4)42[Mo72VIMo60VO372(ClCH2COO)30(H2O)72)] · 250H2O · 15ClCH2COONa (II), in particular, as parts of polymer-containing compositions were studied by EPR, NMR, IR, and Raman spectroscopy. The structural and chemical aspects responsible for the formation of the observed spectra were considered.

Reactions of 3-amino-1-phenyl- and 3-amino-1-(thien-2-yl)-4,4,4-trifluorobut-2-en-1-ones with 1,2-diaminopropane and 1,2-diamino-3,3,3-trifluoropropane

The reactions of 3-amino-1-phenyl-and 3-amino-1-(thien-2-yl)-4,4,4-trifluorobut-2-en-1-ones with 1,2-diaminopropane under kinetically controlled conditions afford mixtures ofcis andtrans isomers of 2-aroylmethyl-4-methyl-2-trifluoromethylimidazolidines. Analogous reactions with 1,2-diamino-3,3,3-trifluoropropane yieldcis-2-aroylmethyl-2,4-bis(trifluoro-methyl)imidazolidines.

3,3,3-Trifluoro-N′-(3-trifluoromethylphenyl)-1,2-propanediamine and its N-mono-and N,N-dicarboxyethyl derivatives: synthesis, protolytic and complexation properties

Abstract3,3,3-Trifluoro-N′-(3-trifluoromethylphenyl)-1,2-propanediamine (5) was synthesized by the reaction of 2-diazo-1,1,1-trifluoro-3-nitropropane or 3,3,3-trifluoro-1-nitropropene with 3-aminobenzotrifluoride followed by the reduction of the nitro group. The Michael 1,4-addition of diamine 5 to acrylic acid occurs only at the N(1) atom and affords N-mono-or N,N-dicarboxyethyl derivatives 6 and 7, depending on the reactant ratio. Protolytic equilibria 5–7 in aqueous solutions were studied by pH-potentiometry and UV spectroscopy. Only the aliphatic amino group can be protonated in an aqueous solution, while the aromatic amino group remains unprotonated even in 12 M HCl. The stability constants of transition metal (Cu2+, Ni2+, Zn2+) complexes with ligands 5–7 were determined by pH-potentiometric titration. The stability of the complexes and selectivity of the ligands toward Cu2+ ions increase with an increase in the number of N-carboxyethyl groups.