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In this issue of Chem, Kondo and co-workers report a facile soft-chemical method for the preparation of layered, electrically conductive hydrogen boride, which is short-range order but amorphous as a result of the geometrical frustration of the terminal B–H bonds. This work offers an alternative route to two-dimensional (2D) boron materials.

A facile synthesis of heavy alkali metal octahydrotriborates (MB3 H8 ; M=K, Rb, and Cs) has been developed. It is simply based on reactions of the pure alkali metals with THF⋅BH3 , does not require the use of electron carriers or the addition of other reaction media such as mercury, silica gel, or inert salts as for previous procedures, and delivers the desired products at room temperature in very high yields. However, no reactions were observed when pure Li or Na was used. The reaction mechanisms for the heavy alkali metals were investigated both experimentally and computationally. The low sublimation energies of K, Rb, and Cs were found to be key for initiation of the reactions. The syntheses can be carried out at room temperature because all of the elementary reaction steps have low energy barriers, whereas reactions of LiBH4 /NaBH4 with THF⋅BH3 have to be carried out under reflux. The high stability and solubility of KB3 H8 were examined, and a crystal structure thereof was obtained for the first time.

Different mechanisms for [NH3BH2NH3]+[BH4]− → NH3BH3 + [NH2BH2]n and [NH4]+[BH3NH2BH3]− → NH3BH2NH2BH3 have been elucidated, which leads to the proposal of a general mechanism as below.

B/N anionic aminoborane linear or branched chain complexes, [BH3(NH2BH2)nH]− (n = 1, 2, and 3) and [BH(NH2BH3)3]−, have been synthesized through the controlled reactions of ammonia borane (NH3BH3) with NaH by adjusting the reactant ratios and reaction temperatures. The possible reaction mechanisms were elucidated based on experimental and theoretical studies.

Herein, a novel photo-induced amine-free radical reductive dehalogenation of inactivated aryl/alkyl bromides and chlorides with a palladium complex is described, which reveals excellent functional group compatibility and broad substrate scope. Extensional transformations for reductive cyclization, dehalogenative deuteration, and intra- and intermolecular radical addition can be achieved smoothly. Mechanistic studies indicate a single-electron photoredox catalytic system with inactivated solvent as the hydrogen atom donor.

An efficient synthetic method for MB3H8 (M = Li and Na) has been developed with improved yields on the basis of the investigation of the interconversion between THFB3H7 and corresponding MB3H8. The mechanism was tentatively proposed based on the understanding of the nucleophilicity of the B-H bonding pair electrons.

Octahydridoborate, i.e. [B3H8](-) containing compounds, have recently attracted interest for hydrogen storage. In the present study, the structural, hydrogen storage, and ion conductivity properties of KB3H8 have been systematically investigated. Two distinct polymorphic transitions are identified for KB3H8 from a monoclinic (alpha) to an orthorhombic (alpha ') structure at 15 degrees C via a second-order transition and eventually to a cubic (beta) structure at 30 degrees C by a first-order transition. The beta-polymorph of KB3H8 displays a high degree of disorder of the [B3H8](-) anion, which facilitates increased cation mobility, reaching a K+ conductivity of similar to 10(-7) S cm(-1) above 100 degrees C. beta-KB3H8 starts to release hydrogen at similar to 160 degrees C, simultaneously with the release of B5H9 and trace amounts of B2H6. KBH4 and K-3(BH4)(B12H12) are identified as crystalline decomposition products above 200 degrees C, and the formation of a KBH4 deficient structure of K3-x(BH4)(1-x)(B12H12) is observed at elevated temperature. The hydrogen-uptake properties of a KB3H8-2KH composite have been examined under 380 bar H-2, resulting in the formation of KBH4 at T >= 150 degrees C along with higher metal hydridoborates, i.e. K2B9H9, K2B10H10, and K2B12H12.

In this paper, CuO hollow microspheres with different shell thickness and porosity have been synthesized using carbonaceous saccharide microspheres as templates according to a modified literature method. These CuO hollow microspheres were characterized and their catalytic properties in the hydrolytic dehydrogenation of ammonia borane (NH3BH3, AB) were examined. A kinetic study indicated that a maximum hydrogen generation rate of 294 mL H2 min−1 (g catalyst)−1 can be achieved at 45 ± 0.2 °C in the present system, which is comparable with that for other reported Cu based catalysts.

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 B2H6 from 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 ha...