Hexafluoridotechnetate(IV) Revisited

Novel synthetic routes to hexafluoridotechnetate­(IV) are reported, and for the first time the single-crystal X-ray structures of several M2[TcF6] salts (M = Na, K, Rb, Cs, NH4, and NMe4) were determined. The ammonium and the alkaline metal salts crystallize in the trigonal space group P3̅m, while the NMe4+ salt belongs to the space group R3̅. [TcF6]2– salts are widely stable in aqueous solution. In alkaline media, however, a slow hydrolysis is observed, and the first hydrolysis product, the dimeric, oxido-bridged complex [F5Tc–O–TcF5]4–, could be studied structurally.