A Simple and Efficient Way to Directly Synthesize Unsolvated Alkali Metal (M = Na, K) Salts of [CB11H12]−

Alkali metal (M = Na, K) salts of the [CB11H12]− anion have attracted increasing attention in many fields such as catalysis and all-solid-state batteries. However, tedious and low-yielding synthetic methods have seriously limited their application in these fields. We developed a facile method for the direct synthesis of the unsolvated potassium and sodium salts of the [CB11H12]− anion in 66% and 68% yields, respectively, by reactions of Na[B11H14] with NaH/NaHMDS (sodium bis(trimethylsilyl)amide), CF3SiMe3 in THF and K[B11H14] with KH, CF3SiMe3 in DME. This method avoids the exchange of cation and significantly simplifies the reaction setup, thus enabling convenient large-scale synthesis. It is believed that this method will support further application of Na[CB11H12] and K[CB11H12] as solid electrolytes for an all-solid-state battery.