DFT studies on the Ru-Catalyzed hydrolysis of Ammonia Borane

Publication date: 30 October 2019Source: Journal of Organometallic Chemistry, Volume 899Author(s): Yang Li, Mengwei Hu, Jiasheng Wang, Wan-Hui WangAbstractAmmonia borane (NH3BH3, AB) was a candidate material for hydrogen storage, and hydrolysis of AB was one of the highly potential processes for which three equivalents of hydrogen may be released. In this article, density functional theory calculations were carried out to examine the Ru(II)-catalyzed hydrolysis of AB for releasing three equivalents of hydrogen. The calculation results support that the mechanism for Ru(II)-catalyzed hydrolysis of AB to release of the first equivalent of H2 includes four major stages: 1) the AB coordination to Ru(II)-catalyst, 2) SN2-type nucleophilic attack of H2O on the activated boron center, 3) the attack of the protic O-H of [H3NBH2(H2O)]+, 4) releasing the first equivalent of H2 and regenerating the Ru(II) catalyst. The feasibility of the out of cycle hydrolysis of aminehydroxyboranes accounting for the second and third equivalents of hydrogen was examined and at the same time an alternative catalytic mechanism was proposed. For comparison, the reaction mechanistic for Ru(II)-catalyzed dehydrogenation of AB was also proposed.Graphical abstract

Source: Journal of Organometallic Chemistry - August 30, 2019 Category: Chemistry Source Type: research