Crystal and molecular structure ofS-methyl(pentafluorosulfanyl)thiocarbamate

The X-ray structure of S-methyl(pentafluorosulfanyl)thiocarbamate, SF₅NHC(O)SCH₃, has been determined from three-dimensional diffractometer data and refined by full-matrix least-squares techniques. The crystals are monoclinic:P2₁/m,a=5.008 (5),b=7.811 (2),c=9.348 (4) Å, =99.08 (7)°, andZ=2; finalR=0.046 for 517 observed reflections. The structure comprises hydrogen-bonded (NHO) chains with the component monomers in thecis, cis-conformation, i.e., the arrangement of the nonhydrogen and nonfluorine atoms is nearly planar, the SF₅ group and the O are in acis position with respect to the C-NH bond, and the O and the CH₃ group are in acis position with respect to the C(O)-S bond. Theoretical methods including MNDO and molecular modeling were used to study the relative stabilities of the four possible conformations of SF₅NHC(O)SCH₃.     

Integral equation formulation for buoyancy-driven convection problems

An integral equation formulation for buoyancy-driven convection problems is developed and illustrated. Buoyancy-driven convection in a bounded cylindrical geometry with a free surface is studied for a range of aspect ratios and Nusselt numbers. The critical Rayleigh number, the nature of the cellular motion, and the heat transfer enhancement are computed using linear theory. Green's functions are used to convert the linear problem into linear Fredholm integral equations. Theorems are proved which establish the properties of the eigenvalues and eigenfunctions of the linear integral operator which appears in these equations.     

Reaktionen des (Pentafluorsulfanyl)dichloramin

Reactions of Pentafluorosulfanyldichloroamine The previously unexplored reaction chemistry of pentafluorosulfanyldichloroamine has now led to the novel compounds SF₅N?PCl₃ and SF₅N?SeCl₂. Even though both compounds are produced in high yield (>80%), they were found to decompose readily at room temperature. SF₅NCl₂ has also been found to react with S₂Cl₂ or SCl₂ to give SF₅N?SCl₂, and with SF₅N?SCl₂ to give SF₅N?S?NSF₅. Finally, the adduct SF₅NH₂ · HCl is formed from SF₅NCl₂ and HCl.     

Pentafluoronitrosulfane, SF5NO2

The synthesis of pentafluoronitrosulfane, SF5NO2, is accomplished either by reacting N(SF5)3 with NO2 or by the photolysis of a SF5Br/NO2 mixture using diazo lamps. The product is purified by treatment with CsF and repeated trap-to-trap condensation. The solid compound melts at -78 degrees C, and the extrapolated boiling point is 9 degrees C. SF5NO2 is characterized by 19F, 15N NMR, IR, Raman, and UV spectroscopy as well as by mass spectrometry. The molecular structure of SF5NO2 is determined by gas electron diffraction. The molecule possesses C2v symmetry with the NO2 group staggering the equatorial S-F bonds and an extremely long 1.903(7) Angstroms S-N bond. Calculated bond enthalpies depend strongly on the computational method: 159 (MP2/6-311G++(3df)) and 87 kJ mol(-1) (B3LYP/6-311++G(3df)). The experimental geometry and vibrational spectrum are reproduced reasonably well by quantum chemical calculations.     

Pentacarbonylchrom-Komplexe SF5-substituierter Isocyanide

Pentacarbonyl Chromium Complexes of SF₅-substituted Isocyanides The syntheses of [(F₅S? N ? CCF₃? NC)Cr(CO)₅], [(F₅S? N ? CC₃F₇? CN)Cr(CO)₅] and [F₅S? N ? C(NCCr(CO)₅)₂] are reported. The structure of the last-named compound, triclinic, P1 , a ? 640.70(10), b ? 1197.5(2), c ? 1423.5(2) pm, α = 92.560(10), β = 63.410(10), γ = 99.710(10)º, Z = 2, R1 = 0.0512, wR2 = 0.1533, has been elucidated by X-ray diffraction. The analogous tellurium compound is thermally unstable and can not be obtained in substance.     

1-Chloro-2,6-dinitro-4-perfluoroalkylthiobenzenes in the Synthesis of Heterocycles

1-Chloro-2,6-dinitro-4-perfluoroalkylthiobenzenes was obtained in first time by perfluoroalkylation of bis(4-chloro-3,5-dinitrophenyl)disulfide in the presence of xenon bisperfluoroalkylcarboxylates. At the interaction of these compounds with potassium ethylxanthogenate only substitution of chlorine atom occurred. The reaction with sodium N,N-dimethyldithiocarbamate leads to the nucleophilic substitution of nitro group with formation of 1,3-benzodithiol-2-one, but on action of ethyl thioglycolate the intramolecular condensation occurs with formation of benzothiazoles N-oxides.