Molecular kinetic aspects of vaporization of volatile coordination compounds with organic ligands

We present results of the experimental study and numerical simulation of radiation-convective heat and mass transfer during the sublimation of spherical particles of metal β-diketonates in a high-temperature inert gas flow (argon or helium). The sublimation process is visualized, and experimental data on the temperature variation dynamics and particle size are obtained. It is shown that at stable transfer of the compound from the particle surface the sublimation proceeds with the formation of large pores in its structure. The effect of inert gas properties on the kinetics of the vaporization process of precursor particles with various initial diameters is analyzed in the temperature range from 200 °C to 330 °C. Due to a higher thermal conductivity and heat capacity of helium as compared with argon, the choice of helium as carrier gas causes an increase in the sublimation intensity.     

EPR study of spin adducts of silyl and phosphonyl radicals with higher internal perfluoroalkenes

The EPR method was used to study the structure of spin adducts of silyl and phosphonyl radicals with higher internal perfluoroalkenes. The capacity for spin adducts to split off hydrogen atoms is determined by the degree of steric screening of the free radical center. The preparative photochemical reaction of hydrosilanes and dialkyl phosphites with perfluoro-4-methylpent-2-ene leads to regiospecific hydrosilylation and hydrophosphorylation products with yields up to 80%.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1018–1023, May, 1991.     

Highly polarized enamines 1. synthesis and some properties ofβ-tetrazolylenamines

A method has been developed for the synthesis of some-tetrazolyl--nitroenamines containing various alkoxy or amino substituents in the a position. It is based on the transformation of a pyrimidine ring by sodium azide.Center for Drug Chemistry, All-Union research Institute of Pharmaceutical Chemistry (VNIKhFI), Moscow 119021 Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 976–980, July, 1994     

Determination of rhenium and osmium complexes by surface-assisted laser desorption/ionization coupled to Orbitrap mass analyzer

A surface-assisted laser desorption/ionization (SALDI) source is coupled to the Orbitrap mass analyzer; the instrumental approach is tested for the analysis of rhenium (Re) and osmium (Os) complexes with 8-mercaptoquinoline. Silicon (Si) material obtained by laser treatment of monocrystalline Si is used as SALDI substrate. All studied complexes are detected as radical cations, with no protonated molecules. The comparison of SALDI, matrix-assisted laser desorption/ionization (MALDI), and direct laser desorption/ionization (LDI) on metal plates in the same instrumental setup demonstrated that the detection of the studied complexes using SALDI provides the highest sensitivity. The ability to analyze samples rapidly, high purity of spectra, and good analytical parameters make SALDI coupled to the Orbitrap mass analyzer a potentially powerful tool for the detection of Re and Os complexes and related organic, UV-absorbing compounds.

Substituted 1,3,2,4‐benzodithiadiazines and related compounds

Despite some limitations, the 1:1 condensation of n‐RC₆H₄‐N=S=N‐SiMe₃ (n = 2, 3, 4; R = CH₃, OCH₃, F, Cl, CF₃) with SCl₂, followed by intramolecular electrophilic ortho‐cyclization, was found to be a general synthetic approach to the corresponding 5‐R, 6‐R, and 7‐R–substituted 1,3,2,4‐benzodithiadiazines, formally antiaromatic 12π‐electron compounds. For precursors with n = 3, the high regioselectivity of the cyclization resulted in exclusive (R = OCH₃, F) or predominant (R = CH₃, Cl) formation of 6‐R isomers; the ratio of the major 6‐R isomer to the minor 8‐R one was found to be 72:28 (R = CH₃) or 78:22 (R = Cl). The preferred direction of cyclization is consistent with thermodynamics of the corresponding intermediate σ‐complexes as well as factors of kinetic control for an orbital‐controlled El‐Nu reaction. According to the X‐ray diffraction data, the molecules of 5‐CF₃ (15) and 6‐F (12) derivatives are nearly planar, while the molecules of 5‐OCH₃ (7) and 6‐CH₃ (4) derivatives are bent along the S¹ … N⁴ line by ∼11° (7) or 7° (4). An attempt to adopt CsF‐induced intramolecular nucleophilic ortho‐cyclization of Ar_F‐S‐N=S=N‐SiMe₃ into polyfluorinated 1,3,2,4‐benzodithiadiazines for polyfluoropyridine derivatives resulted in formation of polyfluorinated aminopyridines. Data obtained are consistent with a previously suggested scheme of sulfur–nitrogen chain shortening during cyclization. Mild acid hydrolysis of the title compounds was shown to be a convenient synthetic route to substituted 2,2′‐diaminodiphenyl disulfides (including polyfluorinated ones) via the corresponding 2‐aminobenzenethiols. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 113–124, 1999     

Magnetic fluorescence and phosphorescence quenching of gas-phase sulfur dioxide

Sulfur dioxide fluorescence and phosphorescence are quenched by a magnetic field. A model is suggested for the qualitative interpretation of the results.

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Gas phase photoreaction of SO2 with n-pentane in the presence of NO

The spectrum of an intermediate, ascribed to nitrosopentane, has been detected in the photolysis of SO₂-pentane-NO mixtures. This may be explained by a radical photolysis mechanism involving an initial H-atom abstraction from the pentane molecule by SO₂.

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Comparative study of NMR spectea of monosubstituted (C5H4X)M(CO)3 (M=Mn,Re)

Conclusions The electron density on the-cyclopentadienyl ligand in cyclopentadienylmanganese tricarbonyl derivatives is higher than in the corresponding cyclopentadienylrhenium tricarbonyl derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2142–2143, September, 1973.