No abstract

Solid state ammonia borane (AB, H3BNH3) has attracted considerable attention as a promising hydrogen storage material. In this paper, electronic structures, bonding characters and hydrogen release mechanism of AB are investigated by first-principles calculations. From electronic structure calculations, we show that B (or N) atom first constructs sp hybrids and then forms covalent bonds with surrounding H atoms. The B–N bonds are formed via B–p and N–p hybridization and are dative in nature. Electron deficiency of B atoms induces a charge transfer, which results in hydrogen bonds and dipole–dipole interactions among H3BNH3 complexes. The hydrogen-bonding energy in AB is estimated to be 15.1 kJ mol−1. The formation enthalpy calculations indicate that, in the initial stage of the hydrogen release process, the H atoms forming an H2 molecule are decomposed from two adjacent H3BNH3 complexes rather than from the same H3BNH3 complex and the process is almost thermoneutral.

In the title compound, [Cu(C7H7N2O)(C7H8N2O)(H2O)]ClO4·H2O, the CuII ion is five-coordinated by the N atoms from the 1-(pyridin-2-yl)ethanone oximate and 1-(pyridin-2-yl)ethan­one oxime ligands and by the water O atom in a distorted square-pyramidal geometry. The two organic ligands are linked by an intra­molecular O—H⋯O hydrogen bond. In the crystal, mol­ecules and ions are linked by O—H⋯O hydrogen-bonding inter­actions, forming chains along the a axis. The perchlorate O atoms are disordered in a 0.58 (2):0.42 (2) ratio.

In the title compound, (C6H16N)[Ni(C9H4N2O3)(C9H5N2O3)], the NiIIion is four-coordinated by two N atoms and two O atoms from two indane-1,2,3-trione-1,2-dioxime ligands. The two organic ligands are linked by an intra­molecular O—H⋯O hydrogen bond. In the crystal, mol­ecules are linked by N—H⋯O hydrogen-bonds.