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.     

3-Nitro-2H-chromenes in [3+2] cycloaddition reaction with azomethine ylides derived from N-unsubstituted α-amino acids and isatins: regio- and stereoselective synthesis of spirochromeno[3,4-c]pyrrolidines

Chemistry of Heterocyclic Compounds - A regio- and stereoselective method was developed for the synthesis of tetrahydro-4H-spiro[chromeno[3,4-c]pyrrole-1,3'-indolin]-2'-ones in 72−96%...     

Reaction of polyhaloalkyl-substituted chromones, pyrones, and furanones with salicylaldehydes as a direct route to fused 2H-chromenes

Polyhaloalkyl-substituted chromones, gamma-pyrones, and beta-furanones react with salicylaldehydes in the presence of piperidine to give a wide variety of fused 2H-chromenes in good yields. This novel annulation reaction presumably proceeds by a tandem intermolecular oxa-Michael addition and subsequent intramolecular Mannich condensation.     

[3+2] Annulation of 2-substituted 3-nitro-2H-chromenes with mercaptoacetaldehyde: stereoselective synthesis of tetrahydro-4H-thieno[3,2-c]chromen-3-ols

Chemistry of Heterocyclic Compounds - A diastereoselective method was developed for the synthesis of 4-trifluoromethyl- and 4-phenyl-substituted...     

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. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1945–1955, November, 2006.     

N-Substituted α-trifluoromethyl β-nitro amines in the synthesis of fluorine-containing 1,2-diamines, amino alcohols, and β-amino acids

Reactions of 2-diazo-1,1,1-trifluoro-3-nitropropane or 1-trifluoromethyl-2-nitroethenes with amines and amino alcohols afforded N-mono- and N,N-disubstituted α-trifluoromethyl β-nitro amines, which were used to obtain a number of trifluoromethyl-containing 1,2-diamines, amino alcohols, and β-amino acids.     

Synthesis of 3‐substituted 2‐trifluoro(trichloro)methyl‐2H‐chromenes by reaction of salicylaldehydes with activated trihalomethyl alkenes

The reaction of activated trihalome‐ thylsubstituted alkenes with salicylaldehydes in the presence of triethylamine gives 3‐substituted 2‐trifluo‐ romethylchroman‐4‐ols and 2‐trifluoro(trichloro)methyl‐2H‐chromenes in high yields. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:492–496, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20146     

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

Molybdenum polyoxometallates with the buckyball structure, ((NH₄)₄₂[Mo₇₂^VIMo₆₀^VO₃₇₂(H₃CCOO)₃₀(H₂O)₇₂] · 30H₃CCOONH₄ · 250H₂O (I), (NH₄)₄₂[Mo₇₂^VIMo₆₀^VO₃₇₂(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.