Selective synthesis of the B11H14− and B12H122− borane derivatives and the general mechanisms of the B-H bond condensation

An Improved Method for the Synthesis of M2[B12H12] (M = Na, K) and Their Formation Mechanism

“…The generation of B 2 H 6 was demonstrated by capturing the exhaust gas by tetrahydrofuran (THF) and obtaining borane–tetrahydrofuran complex (THF·BH 3 ) (Figure S1). However, as reported previously, K[B 3 H 8 ] can react with K[B 11 H 14 ] or K[B 9 H 14 ] in diglyme at 120 °C for 36 h or 140 °C for 3.5 days, respectively, to give the target compound K 2 [B 12 H 12 ] (eqs and ): K false[ normalB 3 normalH 8 false] + K false[ normalB 11 normalH 14 false] → 120 C ° , 36 h diglyme K 2 false[ normalB 12 normalH 12 false] K false[ normalB 3 normalH 8 false] + K false[ normalB 9 normalH 14 false] → 140 C ° , 3.5 days diglyme K 2 false[ normalB 12 …”

“…In the systematical investigation of facile synthetic methods of the polyhedral boranes, we found that the conversion of the polyhedral boranes from borohydrides or an L·BH 3 complex is mainly through the B–H bond condensation reaction. The nature of the B–H bond condensation is the formation of the B–B bond through the dihydrogen bonding interaction, companying with the hydrogen molecule release . Generally, the bridged hydrogen in neutral boranes, such as in B 2 H 6 , B 5 H 9 , and B 10 H 14 , displays a positively charged character, and the terminal hydrogen of boranes displays a negatively charged property.…”

“…In addition to the above three methods, [B 12 H 12 ] 2− can be prepared by reacting borohydrides with I 2 or organic halides (eqs 12−14): 24−26 ) and the dihydrogen bond between the positively charged hydrogen (bridged hydrogens) and the negatively charged hydrogen (terminal hydrogen) play an important role in the process. 27 Herein we report the reaction of MBH…”

“…Therefore, the formation of polyhedral borane compound is related to the basicity of the Lewis bases in borane adducts, which has an important connection with its steric hindrance. 27 According to the literature, 9 1). The results showed the optimal reaction temperatures were 100 to 120 °C.…”

“…The nature of the B−H bond condensation is the formation of the B−B bond through the dihydrogen bonding interaction, companying with the hydrogen molecule release. 27 Generally, the bridged hydrogen in neutral boranes, such as in B 2 H 6 , B 5 H 9 , and B 10 H 14 , displays a positively charged character, and the terminal hydrogen of boranes displays a negatively charged property. Thus, the in situ generation of these neutral boranes is crucial for realizing the dihydrogen interaction.…”