Mechanistic Study of LiNH2BH3 Formation from (LiH)(4) NH3BH3 and Subsequent Dehydrogenation

作者：Lee Tae Bum; McKee Michael L^*

来源：Inorganic Chemistry, 2009, 48(16): 7564-7575.

DOI：10.1021/ic9001835

The formation of LiNH2BH3 from (LiH)(4) and NH3BH3 and the subsequent dehydrogenation have been studied computationally at the CCSD(T)/6-311 G(3d,2p)/MP2/6-311 G(2d,p) level. A cubic unit of (LiH)(4) is predicted to react readily with NH3BH3 to form LiNH2BH3 Plus H-2. The (LiH)(4) tetramer enables dehydrogenation through the exchange of a hydride vertex of (LiH)(4) and NH2BH3- where NH2BH3- is formed when the hydride vertex of (LiH)(4) abstracts a proton from NH3. The free energy of activation for loss of H-2 is reduced from 37.2 kcal/mol in NH3BH3 to 11.0 kcal/mol in (LiH)(4) NH3BH3. Further, H-2 elimination from the (LiNH2BH3)(2) dimer is predicted to be much easier than from the monomer which may suggest a cooperative H-2-loss mechanism is possible in solid LiNH2BH3. While two molecules of H-2 can be lost reversibly from (LiNH2BH3)(2), loss of further H-2 molecules is more difficult but could occur if the lattice energy stabilization accompanying H-2 loss is sufficiently large.

• 出版日期2009-8-17