Complex Transition Metal Hydrides

Compounds having structural units formed by transition metals and hydrogen have only become known fairly recently. Only the synthesis and structural characterization of ternary metal hydrides A x M y H z in which A is an alkali or alkaline‐earth metal and M is a transition metal, led to the discovery of anionic complex groups of the form [MH z ]. Although there are obvious structural similarities to the corresponding halides and oxides, the dynamic properties of the hydride ligand are somewhat unusual and are responsible for numerous phase transformations. Transitions throughout the range from saltlike to metallic behavior make us expect interesting physical properties and applications.