Structure and Bonding of Titanium Alanate

Abstract Titanium alanate Ti(AlH 4 ) 4 is a candidate material for high‐density hydrogen storage that thus far has been scarcely investigated. This study determines the low energy structures of Ti(AlH 4 ) 4 by adopting a global optimization algorithm combined with density functional theories, and systematically compares their stabilities, electronic structures, and bonding properties with Mg(AlH 4 ) 2 and Ca(AlH 4 ) 2 . Compared to other compounds, Ti(AlH 4 ) 4 is less stable and the Ti−H bond is of covalent nature with strong polarities. The covalent Ti−H interaction can weaken the Al−H bonds. Because both the ionic and covalent interactions of the Al−H bonds are the weakest in Ti(AlH 4 ) 4 , it is favorable for the desorption of hydrogen.