Ammonia borane structure

Molecular Simulation of Structural Changes of Ammonia Borane ... 

Kalidindi, S. B. Sanyal, U. Jagirdar, B. R., Nano structured Cu and CuOCujO core shell catalysts for hydrogen generation from ammonia-borane, Phys. Chem. Chem. Phys. 2008,10, 5870-5874. 

The results indicate that hollow structure plays important role to show high activity for hydrolytic dehydrogenation of ammonia borane due to shorter diffusion distance that the reactants for hydrolysis of ammonia borane access to the active sites or larger amount of active site on the hollow spheres compared with the amount on the spherical particles. 

Softer bases will also react with diborane and cause symmetric cleavage. A typical preparation for ammonia borane from diborane that seeks to avoid the salt structure would be to cleave the diborane symmetrically with a soft base, forming a BH3 Soft Base adduct. The soft base is then displaced by ammonia to yield the product, in the desired BH3NII3 form [53]. 

The third approach, this one by Seyferth, is based on the coordinative linkage of borane cage structures by diamines or phosphines to form soluble oligomers (9.21), followed by pyrolysis (reaction (20)).66-68 Pyrolysis in an inert atmosphere gives a 70-90% ceramic yield of a black boron carbonitride, but pyrolysis in ammonia yields white BN in 70% yield. A disadvantage of a process based on a borane starting material is its high cost. 

Ammoniates of boranes. The ammonia addition compound of B2H6 has a molecular weight in liquid ammonia corresponding to the formula B2H6. 2 NH3. An ionic structure NH4 [BH3. NH2- BH3] has been suggested, but the formulation as a borohydride, [H2B(NH3)2] (BH4) , is now preferred. This would appear to be consistent with its reaction with NH4CI ... 

---