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

Abstract

Improved methods for the synthesis of KB3H8, NH3B3H7, and N-alkyl analogues of NH3B3H7 have been developed based on previous works. KB3H8 was synthesized by the reaction of metallic potassium (K) with borane dimethyl sulfide ((CH3)2S·BH3) with high yield and atom-economy. In the preparation of NH3B3H7 and its N-alkyl analogues, KB3H8 served as a starting material and was converted to THF·B3H7 first through reactions with HCl diethyl ether solution or oxidation agent CoCl2. Then, the formed THF·B3H7 in situ reacted with the corresponding ammonia or amines to form the amine borane final products. This work paves an alternative way for preparing organic–inorganic hybrid materials containing B, N, and C atoms.

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

“…The [B 3 H 7 NH 2 BH 2 NH 2 B 3 H 7 ] − anion possesses a structural skeleton of five-membered B/N chain, which is similar to the [BH 3 NH 2 BH 2 NH 2 BH 3 ] − anion 17 and neutral B 3 H 7 NH 2 (CH 2 ) n NH 2 B 3 H 7 ( n = 2, 4) complex. 15 We also attempted to synthesize the sodium salt Na[B 3 H 7 NH 2 BH 2 NH 2 B 3 H 7 ] according to similar methods, but were not successful.2KH + 3NH 3 B 3 H 7 → K[B 3 H 7 NH 2 BH 2 NH 2 B 3 H 7 ] + NH 3 BH 3 + KBH 4 + H 2 2K[NH 2 BH 3 ] + 3NH 3 B 3 H 7 → K[B 3 H 7 NH 2 BH 2 NH 2 B 3 H 7 ] + 2NH 3 BH 3 + KBH 4 + 1/ n [NH 2 BH 2 ] n As shown in Fig. 1, K[B 3 H 7 NH 2 BH 2 NH 2 B 3 H 7 ] exhibits three B signals at −8.55, −17.11, and −25.48 ppm in the 11 B and 11 B{ 1 H} NMR spectra, which are assigned to the B atom of BH 2 , and the four base B atoms and two top B atoms of two B 3 H 7 groups, respectively (the B atom bonding NH 2 named as the top B and the other two B atoms named as the base B in the B 3 H 7 fragment of K[B 3 H 7 NH 2 BH 2 NH 2 B 3 H 7 ]).…”

“…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.…”

“…[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.…”

“…The ionic conductive properties, electrochemical stability, and K-ion transference number have also been measured. Moreover, the ESP of the anions is calculated for comparison with the anion-cation binding interactions in 15 We also attempted to synthesize the sodium salt Na[B 3 H 7 NH 2 BH 2 NH 2 B 3 H 7 ] according to similar methods, but were not successful.…”