Mobility — the transport of people and goods — is a socioeconomic reality that will surely increase in the coming years. It should be safe, economic and reasonably clean. Little energy needs to be expended to overcome potential energy changes, but a great deal is lost through friction (for cars about 10 kWh per 100 km) and low-efficiency energy conversion. Vehicles can be run either by connecting them to a continuous supply of energy or by storing energy on board. Hydrogen would be ideal as a synthetic fuel because it is lightweight, highly abundant and its oxidation product (water) is environmentally benign, but storage remains a problem. Here we present recent developments in the search for innovative materials with high hydrogen-storage capacity.

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Hydrogen-storage materials for mobile applications

Strong Closed-Shell Interactions in Inorganic Chemistry.

This review focuses on key aspects of the thermal decomposition of multinary or mixed hydride materials, with a particular emphasis on the rational control and chemical tuning of the strategically important thermal decomposition temperature of such hydrides, Tdec. An attempt is also made to predict the thermal stability of as-yet unknown, elusive or even unknown hydrides. The future of a particularly promising class of materials for hydrogen storage, namely the catalytically enhanced complex metal hydrides, is discussed. The predictions are supported by thermodynamics considerations, calculations derived from molecular orbital (MO) theory and backed up by simple chemical insights and intuition.

Thermal decomposition of the non-interstitial hydrides for the storage and production of hydrogen.

Shape maps and polyhedral interconversion paths in transition metal chemistry

This review highlights the use and great potential of liquid metals as exotic and powerful solvents (i.e. fluxes) for the synthesis of intermetallic phases. The results presented demonstrate that considerable advances in the discovery of novel and complex phases are achievable utilizing molten metals as solvents. A wide cross-section of examples of flux-grown intermetallic phases and related solids are discussed and a brief history of the origins of flux chemistry is given. The most commonly used metal fluxes are surveyed and where possible, the underlying principal reasons that make the flux reaction work are discussed.

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The metal flux: a preparative tool for the exploration of intermetallic compounds.

The antiferromagnetic structures of KFeS2, RbFeS2, KFeSe2, and RbFeSe2 and the correlation between magnetic moments and crystal field calculations

Complex Transition Metal Hydrides

Li3FeN2 was prepared from the melt under nitrogen and the crystal structure was determined by single-crystal diffraction (Ibam; a = 4872(1) pm, b = 9641(2) pm, c = 4792(1) pm, Z = 4) The crystal structure can be described in terms of a fluorite superstructure which contains infinite chains 1 ∞ [FeN 4 2 3−] of edge-sharing FeN4 tetrahedra Measurements of the magnetic susceptibilities vs temperature reveal Curie-Weiss behaviour Magnetic ordering occurs below 10 K The calculated magnetic moment of 17(1) μB indicates a low spin state of the Fe3+ ion

Li3FeN2, a ternary nitride with ∞1[FeN4/23-]-chains: Crystal structure and magnetic properties

The ternary hydride Na2PdH2 was synthesized by the reaction of sodium hydride with palladium in a hydrogen atmosphere at 370 °C. The structure was derived from X-ray investigations on powdered samples and on a single crystal as well as from neutron diffraction experiments on the deuterated compound. Na2PdH2 crystallizes in the tetragonal space group I4/mmm and is isotypic with Na2HgO2. The atomic arrangement is characterized by a novel linear [PdH2] complex.

Na2PdH2, a hydride with a novel linear [PdH2] complex

Relationships between crystal structure and magnetic properties enable an insight into the nature of the binding of atoms or ions in the solid state. Suitable as model substances are transition metal compounds in which the collective bonds that are generally present are directively degraded by incorporation of diamagnetic cations. This requirement of progressive degradation is met with in sulfides of the general composition AxMySz, where A ≙ alkali metal and M ≙ transition metal.

Welf Bronger

Papers

The antiferromagnetic structures of KFeS2, RbFeS2, KFeSe2, and RbFeSe2 and the correlation between magnetic moments and crystal field calculations

Complex Transition Metal Hydrides

Li3FeN2, a ternary nitride with ∞1[FeN4/23-]-chains: Crystal structure and magnetic properties

Na2PdH2, a hydride with a novel linear [PdH2] complex

Ternary Sulfides: Model Compounds for the Correlation of Crystal Structure and Magnetic Properties