New Syntheses and Structural\nCharacterization of NH₃BH₂Cl and (BH₂NH₂)₃ and Thermal Decomposition Behavior of\nNH₃BH₂Cl

Abstract

New convenient procedures for the preparation of ammonia\nmonochloroborane (NH₃BH₂Cl) and cyclotriborazane\n[(BH₂NH₂)₃] are described. Crystal\nstructures have been determined by single-crystal X-ray diffraction.\nStrong H···Cl···H bifurcated hydrogen\nbonding and weak N–H···H dihydrogen bonding\nare observed in the crystal structure of ammonia monochloroborane.\nWhen heated at 50 °C or under vacuum, ammonia monochloroborane\ndecomposes to (NH₂BHCl)_<i>x</i>, which\nwas characterized by NMR, elemental analysis, and powder X-ray diffraction.\nRedetermination of the crystal structure of cyclotriborazane at low\ntemperature by single-crystal X-ray diffraction analysis provides\naccurate hydrogen positions. Similar to ammonia borane, cyclotriborazane\nshows extensive dihydrogen bonding of N–H···H\nand B–H···H bonds with H^δ+···H^δ− interactions in the range of 2.00–2.34\nÅ.