In Situ Synthesis of WF<sub>6</sub> and ReF<sub>6</sub> in a Diamond\nAnvil Cell and Phase Separation of Products

In\nrecent years, transition metal (TM) fluorides have attracted\nmuch attention due to their novel oxidation states and supercoordination\nunder high pressure. However, the strong oxidation and fluorination\nproperties of TM fluorides limit the research on high-pressure experiment.\nWe propose an experimental protocol for the in situ synthesis of TM\nfluorides in a diamond anvil cell. Solid xenon difluoride (XeF<sub>2</sub>) and Re and W gaskets served as precursors, while liquid\nnitrogen (N<sub>2</sub>) acted as the solvent and pressure-transfer\nmedium. Then, ReF<sub>6</sub> and WF<sub>6</sub> were synthesized\nat less than 90 °C and below 1 GPa and confirmed by Raman spectroscopy\nand microscopic observation. Subsequently, the fluorides were separated\nfrom the pressure-transfer medium by the regulation of pressure and\ntemperature. Our work lays the foundation for researching strong oxidizing\nand fluoridating TM fluorides under high pressure and can also be\nextended to the in situ synthesis of other chemically active TM fluorides.