I. B. Kutyashev

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.

Electrotransport, sorption, and photochemical properties of nanocluster polyoxomolybdates with a toroidal structure

The electrotransport, sorption, and photochemical properties of polyoxometalate NH4)32[MO110VIMO28VO416H6(H2O)58(CH3CO2)6] · xH2O (x ∼ 250) with a toroidal structure are studied. Conditions for studying these characteristics are selected on the basis of data on the stability of POM, in dependence on the concentration and acidity of the medium and the processes of thermal decomposition. A set of independent physical and chemical methods of analysis is used. The possibility of the complexation of toroidal POM with polymer molecules is established. The photostabilizing effect of this POM on polymer molecules is revealed.

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.