The direct synthesis and characterization of alkali metal hexafluorochromates (iii), M^I₃CrF₆

Abstract

The reduction of an aqueous solution of CrO₃ with hydrazine hydrate in the presence of an excess of equimolar amounts of M^I OH and 40% HF yields green, crystalline alkali hexafluorochromates(III), M^I₃CrF₆ (M^I= NH₄, Na, K or Rb), in very high yield. The lithium analogue has been prepared by using Li₂CO₃ instead of lithium hydroxide. The compounds have been characterized by elemental analyses, room temperature magnetic moments, infrared spectra and molar conductivity. Time dependent molar conductivity studies of (NH₄)₃CrF₆ and K₃CrF₆ suggest that the compounds do not undergo decomposition in water at ambient temperatures.