| Popis: |
A sample of MoF 5 was prepared by reaction of MoF 6 (g) and Mo(c). Melting curves of temperature against time established the melting temperature at zero impurity to be 318.85 K, the enthalpy of fusion to be 6.1 kJ mol −1 (±5 per cent), and the cryoscopic impurity of the sample to be 0.15 mole per cent. In the presence of MoF 6 (g), which was added to suppress disproportionation, the vapor density of MoF 5 over the liquid was measured by the transpiration method at 343, 363, and 383 K, the total MoF 5 that evaporated being determined by permanganate titration. The total vapor pressure of MoF 5 oligomers over the liquid was measured by a simple static method at 373 and 392 K, while melting temperatures were taken alternately to monitor possible contamination of the sample. Although the vapor pressures were adjusted for disproportionation, solution of MoF 6 in MoF 5 (1), and wall adsorption of MoF 6 , their percentage uncertainty is probably several times that of the vapor densities. A combination of the two properties indicates the average extent of association of the saturated vapor to be near 2, which is the value for the dimer species (MoF 5 ) 2 . |
