Magnesium and zinc hydride complexes: From fundamental investigations to potential applications in hydrogen storage and catalysis

Safe and convenient storage of hydrogen is one of the biggest near-future challenges. Magnesium hydride has recently gained increased attention as a potential hydrogen storage material. Despite the many advantages, its main problem is the high hydrogen release temperature of 300 °C. Calculations predict a significant decrease upon reduction of the magnesium hydride particle size. This thesis describes syntheses and structures of novel multinuclear magnesium hydride complexes and gives first experimental proof for the relationship between hydrogen release temperatures and cluster size. The magnesium hydride clusters function as molecular model systems for nano-sized hydrogen storage materials and allow precise investigation at the atomic level. The work is extended by similar investigations on zinc hydride clusters.
In order to identify further applications for magnesium, zinc and calcium hydride complexes, the reactivity of selected compounds towards simple substrates like water and pyridine is investigated. Based on the results, alkaline-earth metal hydride complexes are successfully applied as catalysts for the formation of dihydropyridide fragments. The latter are important precursors for the synthesis of various natural products.
Another potential application for magnesium and zinc complexes is as catalysts for the formation of polycarbonates. These biodegradable polymers are particularly interesting as they incorporate undesired carbon dioxide as a useful building block. For this purpose, bimetallic complexes, incorporating magnesium as well as zinc centers in one molecule, are synthesized in order to study potential cooperative effects between these two different metals.