title: Solution-based routes to ammine metal borohydrides: formation of ammonia-borane.
abstract: Ammine metal borohydrides (AMBs) have recently commanded attention as low-temperature hydrogen sources. As an alternative to widely used mechanochemical synthesis that affords mixtures with salt co-products, we have been investigating solution synthesis routes to obtain pure AMBs. Here we show that reactions of MCln + nNaBH4 with ammonia in thf afford ammonia-borane (AB) via borane abstraction from M-coordinated borohydride. The amount of AB formed correlates roughly with the metal ion electronegativity and AMB thermal stability, except for reducible metals such as Ti, which affords nearly 3 equiv. of AB per Ti.
authors.affiliation: Department of Chemistry and Biomolecular Sciences and Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, ON K1N 6N5 Canada. rbaker@uottawa.ca.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Mostajeran
authors.forename: David J
authors.initials: DJ
authors.lastname: Wolstenholme
authors.forename: Chris
authors.initials: C
authors.lastname: Frazee
authors.forename: G Sean
authors.initials: GS
authors.lastname: McGrady
authors.forename: R Tom
authors.initials: RT
authors.lastname: Baker