Theoretical Study of Boron−Ammonia Reactions

The mechanisms of the reactions of a boron atom ( 2 P) and of B 2 ( 3 Σ g - ) with ammonia were studied computationally at the hybrid DFT B3LYP/6-311++G(3df, 2p)//B3LYP/6-311++G(2d,p) level. The B and B 2 insertions into NH bonds take place by initial formation of BNH 3 and BBNH 3 complexes. As found previously for methane and water, B 2 also is more reactive than B with ammonia. The energy-rich boron atom insertion product, HBNH 2, then gives the species HBNH 2, H 2 BNH, HBNH, and BNH. These can react with a second boron atom to give novel boron-containing compounds such as HBNBH, BNBH, H 2 BNBH, and BNB, some of which have been observed experimentally. However, contrary to the experimental suppositions, the only cyclic B 2 N minimum was a high-energy species.