A safe and efficient synthetic method for alkali metal octahydrotriborates, unravelling a general mechanism for constructing the delta B3 unit of polyhedral boranes

Abstract

A safe and efficient synthetic method for MB3H8 (M = Na, K, Rb and Cs) has been developed with excellent yield by directly reacting the corresponding MBH4 with dimethyl sulfideborane...

Improved Methods for the Synthesis of KB3H8, NH3B3H7, and N-Alkyl Analogues of NH3B3H7

“…Then, we further found that the reaction of KBH 4 and (CH 3 ) 2 S•BH 3 (eq 1) can be used to synthesize KB 3 H 8 with high yield, and the similar reaction mechanism was also clarified. 23 In addition, in 2019, our group also illustrated the reaction mechanisms of the pure alkali metals with THF• BH 3 for the preparation of MB 3 H 8 (M = K, Rb, and Cs). 24 Using this reaction (eq 2), the unsolvated KB 3 H 8 was isolated in 90% yield.…”

“…The mechanism of the formation of KB 3 H 8 should be similar to those we have proposed recently. 21,23,24 In the first step of this reaction, KB 3 H 8 and KBH 4 were formed (Figure S2) according to eq 2 and then the formed KBH 4 further reacted with (CH 3 ) 2 S•BH 3 to produce the final product KB 3 H 8 according to eq 1. 23 Although the reaction occurs at 90 °C due to the low reaction activity of (CH 3 ) 2 S•BH 3 , the intermediates also possibly include BH 3 − , BH 3 2− , B 2 H 6 2− , B 3 H 9 2− , and B 2 H 5 − in the first step.…”

“…21,23,24 In the first step of this reaction, KB 3 H 8 and KBH 4 were formed (Figure S2) according to eq 2 and then the formed KBH 4 further reacted with (CH 3 ) 2 S•BH 3 to produce the final product KB 3 H 8 according to eq 1. 23 Although the reaction occurs at 90 °C due to the low reaction activity of (CH 3 ) 2 S•BH 3 , the intermediates also possibly include BH 3 − , BH 3 2− , B 2 H 6 2− , B 3 H 9 2− , and B 2 H 5 − in the first step. 24 Then, the reaction mechanism of KBH 4 with (CH 3 ) 2 S•BH 3 in the second step should be similar to those of BH 4…”

Boron Hydrogen Compounds: Hydrogen Storage and Battery Applications

“…There are several reports in the literature on the synthesis of B , which then adds BH 3 . The efficient synthesis of alkali metal octahydrotriborates (M = Na, K, Rb, Cs) from the reaction of MBH 4 with 2 equivalents of dimethyl sulfide borane was reported [82]. The formation of ion B 2 H 7 − was observed by NMR for the reaction of LiBH 4 with THF.BH 3 in THF [83], and during the solvothermal reaction of BH 4 − with CH 2 Cl 2 at 70 • C [84].…”

Synthesis of K[B3H7NH2BH2NH2B3H7] for a K-ion solid-state electrolyte

“…Recently, our group has systematically investigated the synthetic methods of the alkali metal salts of the [B 3 H 8 ] À anion, and the interconversion of the [B 3 H 8 ] À anion and the neutral complexes of LÁB 3 H 7 . [12][13][14][15][16] The yields of K[B 3 H 8 ] and NH 3 B 3 H 7 using the improved methods reached 90% and 88%, respectively. 14,15 The accumulation of the investigation on K[B 3 H 8 ] and its derivatives facilitates us to develop new K[B 3 H 8 ]-based SSEs with high ionic conductive properties.…”