TUNGSTEN AND MOLYBDENUM FLUORIDES BY METAL EXPLOSIONS

High yields of the volatile hexafluorides of tungsten and molybdenum can be obtained by the electrical explosion of these metals into the relatively inert SF6. This constitutes an extremely facile synthesis route for the metal hexafluorides, because the fluorination of the metals by conventional techniques requires the use of elemental fluorine. Carbon tetrafluoride can also be used for the facile synthesis of WF6 by the metal explosion technique, but is less efficacious than SF6. The reaction path of metal explosions into SF6 depends upon reactant stoichiometry, but the yield of metal hexafluoride is essentially independent of this stoichiometry. Explosion of molybdenum into PF5 leads to the formation of molybdenum trifluoride and new fluorides MoFn, in which n {slanted equal to or less-than} 1. The relative proportions of MoF3 and lower fluorides that form in these reactions depend strongly upon the imparted electrical energy level. Tungsten is less efficacious than molybdenum in abstracting fluorine from PF5. At comparable energy levels tungsten forms only fluorides of low fluorine content. It is indicated that the fluorides in which n < 1 are mixtures of monofluorides with still lower fluorides. The applicability of these results to other metals is discussed. © 1969.