Exploratory Synthesis for Complex Metal Fluorides Using Solid-State Fluorine Sources

We
attempted to synthesize complex metal fluorides via reaction
between metal and solid-state fluorine sources and succeeded in preparing
trirutile-type Li2MoF6 using LiF, the metal
Mo, and CuF2. We also found a new phase of Li2MoF6 that is isostructural with trigonal Li2ZrF6 via a combination of solid-state fluorine sources
and high-pressure synthesis. The reaction occurs exothermically and
involves conversion and addition associated with redox reaction, and
CuF2 then functions as both an oxidizing agent and fluorine
source. Because the overall reaction proceeds stoichiometrically,
the required amount of fluorine can be controlled by the amount of
solid-state fluorine agents. The synthesis route was also applicable
for the preparation of other known fluorides, Li2MF6 (M = Ti, Zr, and Nb) and β-Li3MF6 (M = Ti and V). The synthetic route using a solid-state fluorine
source is suitable for the exploration of novel inorganic complex
metal fluorides.