title: Insights into metal borohydride and aluminohydride bonding: X-ray and neutron diffraction structures and a DFT and charge density study of [Na(15-crown-5)][EH(4)] (E = B, Al).
abstract: The neutron and X-ray structures of [Na(15-crown-5)][BH(4)] and [Na(15-crown-5)][AlH(4)], respectively, are reported, along with a topological analysis of their DFT-computed charge densities that explores the bonding between the anionic complex hydride [EH(4)](-) (E = B, Al) and the counterion [Na(15-crown-5)](+). In each case, the interaction is weak and mainly electrostatic in nature; however, notable differences are observed in the manner in which [BH(4)](-) and [AlH(4)](-) bind to the metal, which explains their different coordination modes. A range of unconventional E-H···H-C contacts is revealed to play an important role in the overall bonding and crystal packing of both complexes. These interactions can be classified as weak dihydrogen bonds based on the atoms in molecules approach.
authors.affiliation: Department of Chemistry, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 5A3. psirsch@unb.ca
authors.forename: Peter
authors.initials: P
authors.lastname: Sirsch
authors.forename: Natascha L N
authors.initials: NL
authors.lastname: Clark
authors.forename: Lenuţa
authors.initials: L
authors.lastname: Onuţ
authors.forename: Richard P L
authors.initials: RP
authors.lastname: Burchell
authors.forename: Andreas
authors.initials: A
authors.lastname: Decken
authors.forename: G Sean
authors.initials: GS
authors.lastname: McGrady
authors.forename: Aziz
authors.initials: A
authors.lastname: Daoud-Aladine
authors.forename: Matthias J
authors.initials: MJ
authors.lastname: Gutmann