Synthesis, Crystal Structure, and Thermal Decomposition of Strontium Amidoborane

Abstract

Strontium amidoborane, Sr(NH2BH3)2, is synthesized by gently milling the powder mixtures of SrH2 and ammonia borane (in a 1:2 molar ratio), followed by isothermally processing the postmilled mixtures at 45 °C for 2 h. It is found that Sr(NH2BH3)2 crystallizes with a monoclinic structure in space group C2, with lattice parameters a = 8.1660(4) Å, b = 5.0969(3) Å, c = 6.7258(4) Å, and β = 94.392(4)°, and with Z = 2. In the structure, each Sr2+ bonds with two [NH2BH3]2− ions with a Sr−N distance of 2.68 Å. Thermal analyses show that the decomposition of Sr(NH2BH3)2 into Sr(NBH)2 and H2 initiates at about 60 °C and becomes violent as the temperature increases to 93 °C in the heating process at a rate of 2 °C min−1. With the release of H2, a considerable amount of NH3 and small amounts of B2H6 are also emitted due to the decomposition of Sr(NBH)2.