title: Metal borohydrides and derivatives - synthesis, structure and properties.
abstract: A wide variety of metal borohydrides, MBH4, have been discovered and characterized during the past decade, revealing an extremely rich chemistry including fascinating structural flexibility and a wide range of compositions and physical properties. Metal borohydrides receive increasing interest within the energy storage field due to their extremely high hydrogen density and possible uses in batteries as solid state ion conductors. Recently, new types of physical properties have been explored in lanthanide-bearing borohydrides related to solid state phosphors and magnetic refrigeration. Two major classes of metal borohydride derivatives have also been discovered: anion-substituted compounds where the complex borohydride anion, BH4-, is replaced by another anion, i.e. a halide or amide ion; and metal borohydrides modified with neutral molecules, such as NH3, NH3BH3, N2H4, etc. Here, we review new synthetic strategies along with structural, physical and chemical properties for metal borohydrides, revealing a number of new trends correlating composition, structure, bonding and thermal properties. These new trends provide general knowledge and may contribute to the design and discovery of new metal borohydrides with tailored properties towards the rational design of novel functional materials. This review also demonstrates that there is still room for discovering new combinations of light elements including boron and hydrogen, leading to complex hydrides with extreme flexibility in composition, structure and properties.
authors.affiliation: Center for Materials Crystallography, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark. trj@chem.au.dk.
authors.forename: Mark
authors.identifier: http://orcid.org/0000-0003-2677-3434
authors.initials: M
authors.lastname: Paskevicius
authors.affiliation: Center for Materials Crystallography, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark. trj@chem.au.dk.
authors.forename: Lars H
authors.initials: LH
authors.lastname: Jepsen
authors.affiliation: Laboratory of Crystallography, DQMP, University of Geneva, 1211 Geneva, Switzerland.
authors.forename: Pascal
authors.initials: P
authors.lastname: Schouwink
authors.affiliation: Laboratory of Crystallography, DQMP, University of Geneva, 1211 Geneva, Switzerland.
authors.forename: Radovan
authors.initials: R
authors.lastname: Černý
authors.affiliation: Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark.
authors.forename: Dorthe B
authors.initials: DB
authors.lastname: Ravnsbæk
authors.affiliation: Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Place L. Pasteur 1, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Yaroslav
authors.initials: Y
authors.lastname: Filinchuk
authors.affiliation: Helmholtz-Zentrum Geesthacht, Department of Nanotechnology, Max-Planck-Straße 1, 21502 Geesthacht, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Dornheim
authors.affiliation: Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, DK-8000 Aarhus C, Denmark.
authors.forename: Flemming
authors.initials: F
authors.lastname: Besenbacher
authors.affiliation: Center for Materials Crystallography, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark. trj@chem.au.dk.
authors.forename: Torben R
authors.identifier: http://orcid.org/0000-0002-4278-3221
authors.initials: TR
authors.lastname: Jensen