An Improved Method to Synthesize M 2 [B 12 H 12 ] (M = Li, Na) by the Sequential Addition of Different Solvents

Abstract The derivatives of [B 12 H 12 ] 2− anion are an important part of polyhedral boranes and play a significant role in the fields of energy, materials, and biomedicine. The researchers have made a great effort to explore the efficient method to synthesize the [B 12 H 12 ] 2− salts. However, the reported synthetic strategies are limited by the requirement of using toxic starting materials, harsh reaction conditions, and tedious and difficult work‐up processes. Herein, we developed an efficient method to synthesize [B 12 H 12 ] 2− salts with MBH 4 (M = Li, Na) and N,N ‐dibutylbenzenamine borane as the starting materials and by adding two kinds of solvents (DME and 1,4‐dioxane or THF and 1,4‐dioxane) into the system in a sequential order. M 2 [B 12 H 12 ] (M = Li, Na) was synthesized in 75%–86% yields, respectively. This method avoids high boiling point ether solvents and flammable, toxic starting materials. Moreover, the developed method is simple and efficient, as the products can precipitate from the reaction system, greatly simplifying the separation process.