13470-13-8Relevant articles and documents
Beyond the conventional number of electrons in M6X12 type metal halide clusters: W6Cl18, (Me4N) 2[W6Cl18], and Cs2[W 6Cl18]
Dill, Simone,Glaser, Jochen,Stroebele, Markus,Tragl, Sonja,Meyer, H.-Juergen
, p. 987 - 992 (2004)
Black octahedral single crystals of W6Cl18 were obtained by reducing WCl4 with graphite in a silica tube at 600°C. The single crystal structure refinement (space group R 3, Z = 3, a = b = 1498.9(1) pm, c = 845.47(5) pm) yielded the W6Cl 18 structure, already reported on the basis of X-ray powder data. (Me4N)2[W6Cl18] and Cs 2[W6Cl18] were obtained from methanolic solutions of W6Cl18 with Me4NCl and CsCl, respectively. The structure of (Me4N)2[W 6Cl18] was refined from X-ray single crystal data (space group P 3ml, Z = 1, a = b = 1079.3(1) pm, c = 857.81(7) pm), and the structure of Cs2[W6Cl18] was refined from X-ray powder data (space group P 3, Z = 1, a = b = 932.10(7) pm, c = 853.02(6) pm). The crystal structure of W6Cl18 contains molecular W6Cl18 units arranged as in a cubic closest packing. The structures of (Me4N)2[W6Cl18] and Cs2[W6Cl18] can be considered as derivatives of the W6Cl18 structure in which 2/3 of the W 6Cl18 molecules are substituted by Me4N + ions and Cs+ ions, respectively. The conventional number of 16 electrons/cluster is exceeded in these compounds, with 18 electrons for W6Cl18 and 20 electrons for (Me4N) 2[W6Cl18] and Cs2[W 6Cl18]. Cs2[W6Cl18] exhibits temperature independent paramagnetic behaviour.
KINETICS OF TUNGSTEN ETCHING BY ATOMIC AND MOLECULAR CHLORINE.
Balooch,Fischl,Olander,Siekhaus
, p. 2090 - 2095 (1988)
The reactions of atomic and molecular chlorine with tungsten were studied by modulated beam-mass spectrometric methods over the temperature range 300-1350 K. The atomic beam was generated by an rf plasma discharge. With both atomic and molecualr beams, the main reaction product up to about 1000 K was WCl//4. The reaction probability with atomic chlorine was a factor of approximately ten higher than that obtained with molecular chlorine. The reaction was nonlinear with respect to Cl//2 intensity at low beam fluxes but approached linearity at high beam intensities. Above 1000 K the main reaction product was atomic chlorine. Its reaction probability increased rapidly with temperature; at 1300 K nearly complete dissociation of Cl//2 was observed. A kinetic model based on the Eley-Rideal mechanism was proposed and compared with the data. AA. 20 Refs.
Synthesis and characterization of carbon- and nitrogen-centered (Z) trigonal prismatic tungsten clusters of the formula type A[W6ZCl 18]
Weisser, Martina,Burgert, Ralf,Schnoeckel, Hansgeorg,Meyer, H.-Juergen
, p. 633 - 640 (2008)
Solid state reactions of tungsten(IV) chloride and carbodiimides (cyanamides) of lithium, sodium, calcium and silver yielded black crystalline powders of centered (Z) trigonal-prismatic tungsten cluster compounds having the general formula A[W6ZCl18] with A = Li, Na, Ca, Ag and Z = C, N. Crystal structures of the corresponding compounds were investigated by powder and single-crystal X-ray diffraction. The nature of the central atom was studied by mass spectrometry and nuclear magnetic resonance spectrometry. It turned out that the central atom can be C (in the case of the lithium and sodium compound) or N (in the case of the sodium and calcium compound).
Two tungsten nitride chlorides: W2NCl8 and W 2NCl9
Weisser, Martina,Tragl, Sonja,Meyer, H.-Juergen
, p. 802 - 806 (2007)
A solid state reaction of tungsten(VI)chloride and cyanamide yielded black crystals of W2NCl8 and red plate-like crystals of W 2NCl9. The structures of these compounds were determined by single crystal X-ray diffraction. The crystal structure of W 2NCl8 contains [Cl2/2Cl3WNWCl 3Cl2/2]-units forming chains along the c-axis. The tungsten atoms are linked by a symmetric nitrido bridge (d(W-N) = 1.8203(4) A). The crystal structure of W2NCl9 contains a dichloro-bridged dimer of a nitride-bridged ditungsten unit [Cl 5WNWCl3Cl2/2]2 with two different W-N distances of 1.726(9) A and 2.012(9) A.
Unprecedented W2(0) quadruply bonded complex supported by π-donor ligands
Ventura,Prat,Aguirre Quintana,Goos,Villagran
supporting information, p. 3974 - 3976 (2016/03/16)
A quadruply bonded complex W2(DippF)2K2 with a W2(0) core was synthesized and structurally characterized. The observed W-W distance of 2.407(1) ? and DFT calculations are consistent to the unprecedented electronic structure in D2h symmetry of σ2π2π2δ2 δ2δ?2 where the HOMO is the δ? orbital.
Kinetic study of Hubnerite (MnWO4) chlorination
Fouga,Taddeo,Bosco,Bohé
, p. 30 - 40 (2012/05/31)
The kinetics of Argentinean Hubnerite (MnWO4) chlorination using gaseous chlorine as chlorination agent was studied between 750 and 950 °C. The relative mass change during the chlorination reaction was continuously monitored using a high resolution thermogravimetric system. The starting temperature for the reaction of the manganese tungstate with chlorine was determined at about 650°C. The influence of gaseous flow rate, sample mass, chlorine partial pressure, and temperature on the reaction rate was analyzed. The dependence of the reaction rate with sample mass clearly indicates that the reaction is not occurring under chemical control, so the reaction proceeds under mixed control for sample masses greater than 0.5 mg. In those conditions, an apparent activation energy of 198 ± 9 kJ mol-1 was obtained with an isoconversional method. Concerning the influence of chlorine partial pressure, it was determined that pressures greater than 35 kPa do not modify the kinetic regime. For the experiment at 850°C, it was found that the chlorination rate was proportional to a potential function of the partial pressure of chlorine whose exponent is around 0.85. Finally, a global rate equation that includes these parameters was developed.
