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 Li 2 MoF 6 using LiF, the metal Mo, and CuF 2 . We also found a new phase of Li 2 MoF 6 that is isostructural with trigonal Li 2 ZrF 6 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 CuF 2 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, Li 2 MF 6 (M = Ti, Zr, and Nb) and β-Li 3 MF 6 (M = Ti and V). The synthetic route using a solid-state fluorine source is suitable for the exploration of novel inorganic complex metal fluorides.