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Boron compounds are well-known electrophiles. Much less known are their nucleophilic properties. By recognition of the nucleophilicity of the B-H bond, the formation mechanism of octahydrotriborate (B3H8-) was elucidated on the bases of both experimental and computational investigations. Two possible routes from the reaction of BH4- and THF-BH3 to B3H8- were proposed, both involving the B2H6 and BH4- intermediates. The two pathways consist of a set of complicated intermediates, which can convert to each other reversibly at room temperature and can be represented by a reaction circle. Only under reflux can the B2H6 and BH4-intermediates be converted to B2H5- and BH3(H2) via a high energy barrier, from which H2 elimination occurs to yield the B3H8- final product. The formation of B2H6from THF-BH3 by nucleophilic substitution of the B-H bond was captured and identified, and the reaction of B2H6 with BH4- to produce B3H8- was confirmed experimentally. On the bases of the formation mechanisms of B3H8-, we have developed a facile synthetic method for MB3H8 (M = Li and Na) in high yields by directly reacting the corresponding MBH4salts with THF-BH3. In the new synthetic method for MB3H8, no electron carriers are needed, allowing convenient preparation of MB3H8 in large scales and paving the way for their wide applications. [ABSTRACT FROM AUTHOR]

The BCN-heterocyclic B-N chain compounds, the sodium and potassium salts of 3 and 4 anions (Na 3 , Na 4 , and K 4 ), were synthesized by reactions of ethane 1,2-diamineborane (BH 3 NH 2 CH 2 CH 2 NH 2 BH 3 , 1 ) and propane 1,2-diamineborane (BH 3 NH 2 CH 2 CH 2 CH 2 NH 2 BH 3 , 2 ) with MH (M = Na and K). Then, the neutral B-N chain compounds 5 and 6 were prepared with dehydrogenation of [NH 4 ] 3 and [NH 4 ] 4 , formed by metathesis reactions of Na 3 and Na 4 with NH 4 Cl or NH 4 SCN, respectively. Compounds 7 and 8 , analog 5 , were also prepared using pyridine and 4-methoxypyridine instead of NH 3 in 5 . These synthesized compounds were characterized spectroscopically, and the singe-crystal structures of the Na 3 ·18-crown-6 and K 4 ·18-crown-6 adducts were determined. Furthermore, the reactions of Na 3 and Na 4 with cationic B-N chain compounds, [NH 3 BH 2 NH 3 ]Cl and [NH 3 BH 2 NH 2 BH 2 NH 3 ]Cl, could not form longer BCN-heterocyclic B-N chain. The solubility of metal hydrides, the ability for proton abstracting, the basicity of Lewis bases, and the chelate effect may influence these reactions even though the reaction mechanism is not fully understood.

The design, synthesis, and applications of new boranes are eternal topics in boron chemistry. A new bis(borane)alkanethiolate salt, K[BH 3 S(CH 3 )BH 3 ], was synthesized in high yield by the reaction of K with (CH 3 ) 2 S·BH 3 at room temperature. The formation mechanism was elucidated based on experimental and theoretical studies. The single-crystal structure of the K[BH 3 S(CH 3 )BH 3 ]·18-crown-6 adduct was determined in which the B-S-B bonding information of K[BH 3 S(CH 3 )BH 3 ] was illustrated for the first time. Using K[BH 3 S(CH 3 )BH 3 ] as a starting material, KB 3 H 8 was successfully synthesized.

All-solid-state potassium batteries are promising candidates in the fields of large-scale energy storage owing to their intrinsic safety, stability, and cost-effectiveness. However, a suitable solid-state electrolyte with high ionic conductivity and favorable interfacial stability is a major challenge for the design and development of these batteries. Herein, we report the synthesis of new KB 3 H 8 · n NH 3 B 3 H 7 ( n = 0.5 and 1) complexes to develop suitable solid-state K-ion conductors for batteries. Both the complexes undergo a reversible phase transition below the thermal decomposition temperature. The optimal KB 3 H 8 ·NH 3 B 3 H 7 delivers a solid-state K-ion conductivity of 1.3 × 10 -4 S cm -1 at 55 °C with an activation energy of 0.44 eV after a transition from a monoclinic to an orthorhombic phase, which is the highest value of K borohydrides reported to date and places KB 3 H 8 ·NH 3 B 3 H 7 among the leading solid-state K-ion conductors. Moreover, KB 3 H 8 ·NH 3 B 3 H 7 reveals a K-ion transference number of nearly 0.93, an electrochemical stability window of 1.2 to 3.5 V vs K + /K, a good capability of K dendrite suppression, and a remarkable stability against the K metal anode due to the formation of the stable interface. These performances make KB 3 H 8 ·NH 3 B 3 H 7 a promising electrolyte for all-solid-state potassium batteries.

Improved methods for the synthesis of KB 3 H 8 , NH 3 B 3 H 7 , and N -alkyl analogues of NH 3 B 3 H 7 have been developed based on previous works. KB 3 H 8 was synthesized by the reaction of metallic potassium (K) with borane dimethyl sulfide ((CH 3 ) 2 S·BH 3 ) with high yield and atom-economy. In the preparation of NH 3 B 3 H 7 and its N -alkyl analogues, KB 3 H 8 served as a starting material and was converted to THF·B 3 H 7 first through reactions with HCl diethyl ether solution or oxidation agent CoCl 2 . Then, the formed THF·B 3 H 7 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.

The reactions of sodium amidoborane (NaNH 2 BH 3 ) with NiBr 2 have been investigated, and the results showed that black precipitate 1 including the NiBNH x composites could be obtained. From the aqueous solution of the precipitate 1 , the hydrolysis product Ni-B ( 2 ) was isolated and characterized. Both the in situ formed precipitate 1 and the hydrolysis product 2 can catalyze the formation of Na[BH 3 (NH 2 BH 2 ) 2 H]. CoCl 2 showed comparable performance with NiBr 2 . Based on these results, a facile method for the synthesis of Na[BH 3 (NH 2 BH 2 ) 2 H] has been developed. This work provides insights into studying experimental methods for the synthesis of long B/N chain complexes and developing boron and nitrogen chemistry.

Boron compounds are well-known electrophiles. Much less known are their nucleophilic properties. By recognition of the nucleophilicity of the B-H bond, the formation mechanism of octahydrotriborate (B 3 H 8 - ) was elucidated on the bases of both experimental and computational investigations. Two possible routes from the reaction of BH 4 - and THF·BH 3 to B 3 H 8 - were proposed, both involving the B 2 H 6 and BH 4 - intermediates. The two pathways consist of a set of complicated intermediates, which can convert to each other reversibly at room temperature and can be represented by a reaction circle. Only under reflux can the B 2 H 6 and BH 4 - intermediates be converted to B 2 H 5 - and BH 3 (H 2 ) via a high energy barrier, from which H 2 elimination occurs to yield the B 3 H 8 - final product. The formation of B 2 H 6 from THF·BH 3 by nucleophilic substitution of the B-H bond was captured and identified, and the reaction of B 2 H 6 with BH 4 - to produce B 3 H 8 - was confirmed experimentally. On the bases of the formation mechanisms of B 3 H 8 - , we have developed a facile synthetic method for MB 3 H 8 (M = Li and Na) in high yields by directly reacting the corresponding MBH 4 salts with THF·BH 3 . In the new synthetic method for MB 3 H 8 , no electron carriers are needed, allowing convenient preparation of MB 3 H 8 in large scales and paving the way for their wide applications.