TECHNICAL REPORTS NO. 28 AND 29. 28. THE VAPOUR PRESSURES OF SOME HEAVY TRANSITION METAL HEXAFLUORIDES. 29. VAPOUR PRESSURES OF SOME FLUORIDES AND OXYFLUORIDES OF MOLYBDENUM, TUNGSTEN, RHENIUM AND OSMIUM
The vapor pressures of the hexafluorides of tungsten, molybdenum, rhenium, osmium, and iridium were measured by a static method using a diaphragm gage of high sensitivity. Hitherto-unknown solid-solid transitions are reported for rhenium, osmium, and iridium hexafluorides together with those known for tungsten and molybdenum hexafluorides. These are respectively: -1.9 deg , - 0.4 deg , + 0.4 deg , -8.2 deg , and -8.7 deg . From the vapor-pressure data more accurate physical constants, latent heats of vaporization and sublimation, heats of fusion and transition, and entropics of fusion, transition and vaporization were calculated. Nuclear magnetic resonance studies with both solid and liquid hexafluorides suggest that there is molecular rotation in the solid state above the transition point. The vapor pressures of the pentafluorides ReF/sub 5/, MoF/ sub 5/, OsF/sub 5/; the oxytetrafluorides ReOF/sub 4/, MoOF/sub 4/, WOF/sub 4/; and the oxyfluorides ReOF/sub 5/ and ReO/sub 2/F/sub 3/ were measured by a static method using a diaphragm gage of high sensitivity. The physical constants, heats of sublimation and vaporization, and entropies of vaporization were derived from the vapor-pressure data. The oxypentafluoride ReOF/sub 5/ was studied in detail and a hitherto-unknown solid-solid transition at 30.0 deg is reported. The thermal disproportionation of the pentafluorides is described. (auth)
- Research Organization:
- Westington. Univ., Seattle
- NSA Number:
- NSA-15-002616
- OSTI ID:
- 4131353
- Report Number(s):
- NP-9270; NR 093-348
- Country of Publication:
- United States
- Language:
- English
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