Na[Li(NH2BH3)(2)] - the first mixed-cation amidoborane with unusual crystal structure

We describe the successful synthesis of the first mixed-cation (pseudoternary) amidoborane, Na[Li(NH2BH3)(2)], with theoretical hydrogen capacity of 11.1 wt%. Na[Li(NH2BH3)(2)] crystallizes triclinic (P (1) over bar ) with a = 5.0197(4) angstrom, b = 7.1203(7) angstrom, c = 8.9198(9) angstrom, alpha = 103.003(6)degrees, beta = 102.200(5)degrees, gamma = 103.575(5)degrees, and V = 289.98(5) angstrom(3) (Z = 2), as additionally confirmed by Density Functional Theory calculations. Its crystal structure is topologically different from those of its orthorhombic LiNH2BH3 and NaNH2BH3 constituents, with distinctly different coordination spheres of Li (3 N atoms and 1 hydride anion) and Na (6 hydride anions). Na[Li(NH2BH3)(2)], which may be viewed as a product of a Lewis acid (LiNH2BH3)/Lewis base (NaNH2BH3) reaction, is an important candidate for a novel lightweight hydrogen storage material. The title material decomposes at low temperature (with onset at 75 degrees C, 6.0% mass loss up to 110 degrees C, and an additional 3.0% up to 200 degrees C) while evolving hydrogen contaminated with ammonia.