Crystal and molecular structure of (Z)-5,6-dihydro-8(7H)quinolinone thiosemicarbazone

The crystal structure of (Z)-5,6-dihydro-8(7H)quinolinone thiosemicarbazone has been determined by X-ray diffraction techniques in order to confirm the identity of this analog of the antineoplastic agent 2-formylpyridine thiosemicarbazone and to determine the nature of the hydrogen bonding in the solid state. The crystals are pale yellow, space groupP2₁/n, witha = 7.682(3),b = 10.168(8),c = 14.795(5) Å, = 103.11(4) °, andZ = 4. The structure was solved by direct methods and refined to a finalR value of 0.017. The molecule is quite planar, with the obvious exception of the central saturated carbon, and this, along with a short C-C bond at the point of attachment of the side chain, appears to be due to an interaction with the pyridyl ring. The molecules are arranged in pairs held together by mutual intermolecular SN hydrogen bonds. There is also an extensive system of intramolecular NN hydrogen bonds.     

Crystal structure of the orange isomer of [(C6H5)3P]2[C2S2(CF3)2]RuCO

The structure of the title compound has been determined by X-ray analysis. It is monoclinic:a = 10.147,b = 10.081,c = 38.627 Å, β = 102.27 °,Z = 4,P2₁/c. The structure was solved by standard methods and refined by least squares to a (conventional)R-factor of 4.7%. The Ru atom is in square-pyramidal configuration: the Ru-S distances (2.286, 2.336Å) are significantly different, but the Ru-P distances average to 2.389 Å. Comparisons are made with the violet isomer.     

The X-ray crystal structure of 3-ammonium-4-hydroxyphenylarsonic acid chloride dihydrate

The X-ray crystal structure of 3-ammonium-4-hydroxyphenylarsonic acid chloride dihydrate has been determined from single-crystal diffraction data. The compound crystallizes in the orthorhombic space groupPna 2₁ with four molecules in a unit cell of dimensionsa=17.712(7),b=13.468(4), andc=4.798(2) Å. The structure was solved by the Patterson method and refined to a finalR value of 2.1%. The average C-C phenyl distance is 1.393 Å, but two bonds are somewhat shorter than the others. This, coupled with the fact that the C-O and C-As bonds are shorter than normal, makes it appear as if there is a minor resonance contributor of a keto form. The C-N bond length of 1.443 Å is intermediate between values found in aminophenols and other ammoniumphenols. The H₂AsO₃ group is nearly tetrahedral, with the double-bonded oxygen rotated 9° out of the phenyl plane about the C-As bond. There is an extensive hydrogen-bonding system, involving every one of the OH and NH hydrogens, through the chloride and the waters of crystallization.     

The crystal and molecular structure of one of the possible conformers of “the smallest piece of ice”—A solid-state isolation of a hydrogen bonded water hexamer trapped within channels of a crystal of a dirhodium molecule

Reexamination of our study of [Rh₂(HNOCCH₃)₄(2H₂O)] 3H₂O (Ahsan, M.Q.; Bernal, I.; Bear, J.L. Inorg. Chem. 1986, 26 260) showed it to be interesting not just because the dirhodium molecule is an antineoplastic but because it contains a hexameric cluster of waters trapped in Rh–Rh lattice cavities. It may well provide an interesting model for the smallest piece of ice (Nauta, K.; Miller, R.E. Science 2000, 287, 293).     

Finite‐dimensional asymptotic behavior in a thermosyphon including the Soret effect

We analyse the dynamics of a fluid transporting a soluble substance in the interior of a closed loop of arbitrary geometry and subjected to the action of gravity and natural convection. After obtaining the governing equations and analysing the well posedness of the system we prove the existence of a global attractor. Finally, using inertial manifold techniques, we obtain an explicit reduced system of ODE's that describes the asymptotic behaviour of the full system. Copyright © 1999 John Wiley & Sons, Ltd.     

Differences in thermal decomposition of Ag(I), Mn(II), Fe(II) and Fe(III) complexes of cyclic dithiocarbamates

The thermal decomposition of pyrrolidinedithiocarbamate (Pyr) and piperidinedithiocarbamate (Pip) complexes of Ag(I), Mn(II), Fe(II) and Fe(III) have been investigated by thermogravimetry and differential scanning calorimetry. The decomposition intermediates and final products were identified from their X-ray diffraction patterns. Changes in their IR spectra were correlated with their thermogravimetric profiles. The hydrated compounds decomposed without loss of water and oxides were detected as the final decomposition products even in nitrogen atmosphere.     

Use of deactivated fused-silica capillary precolumns in pesticide analysis by gas chromatography with electron-capture detection.

The advantages and disadvantages of coupling a retention gap of fused-silica between the injection port and the chromatographic column are discussed. The influence on the peak width and height of several factors such as the solvent (n-hexane, acetone, ethyl acetate and methanol), the gap (length, inner diameter, deactivation mode), the injection volume and the pesticide concentration has been examined. Those factors have very different incidences so, it is not possible to extract a general recommendation about the use of gaps. For this reason, checking its viability in each particular case is more advisable.     

A new chemical bath deposition method for fabricating ZnS,Zn(OH)<Subscript>2</Subscript>, and ZnO thin films,and the optical and structural characterization of these materials

ZnS thin films were deposited on glass and polymer substrates using a reaction between thiourea and a stable zinc complex, Zn(en)₃SO₄ (en: ethylenediamine) or Zn(trien)(ClO₄)₂ (trien: triethylenetetraamine), in alkaline media. In a weak alkaline solution, Zn(OH)₂ films were formed. The deposition reactions were controlled by the supply of sulfide ions from thiourea at a suitable rate in alkaline media and by the dissociation of free-metal ions from the metal complex used, the stability of which defined the free Zn²⁺ concentration throughout the reaction. The ZnS films showed emission peaks at ca. 450 and 485 nm, and the transmittance decreased with decreasing wavelength of the incident light in the visible region of the spectrum. ZnO thin films were deposited by decomposition of Zn(en)₃SO₄ in the presence of Cu(en)₂(ClO₄)₂ and thiourea; the copper(II) complex catalyzes this reaction. The ZnO films exhibited an emission peak at ca. 420 nm, and the absorbance was constant in the visible region of the spectrum. The scanning electron microscope images showed the formation of a fairly uniform surface with fine crystalline particles. PACS 81.15.-z; 68.55.-a; 81.05.Dz     

The preparation und unusual rearrangement of triply bridged μ-heteromethylenecobalt complexes. Molecular structure of μ-ethoxycarbonylmethylenebis[carbonyl-(η5-cyclopentadienyl)cobalt] (CoCo)

the μ-heteromethylenecobalt complexes, which have been synthesized by photolysis of (η⁵-C₅H₅)Co(CO)₂ in the presence of the corresponding diazoacetates at < ?90°C in tetrahydrofuran, undergo a novel type of intramolecular irreversible rearrangement yielding two isomers. The structure of one of the isomers has been established by X-ray analysis. A comparison of the structural parameters of all known μ-methylene-transition metal complexes shows that the internal angles α of the cyclopropane-like systems are far less sensitive to the compositions and structures of the molecules than the external angles β. The internal angles cannot be readily correlated with other features of the molecule.