The reversible synthesis of bis(quinuclidine) alane

Abstract Aluminum hydride is a material that is well known for its high gravimetric and volumetric hydrogen densities and thus is an attractive hydrogen storage compound; however, it is thermodynamically unstable at room temperature requiring 7 × 10 3  bar pressure to reform the hydride from Al and H 2 . An alternate method of AlH 3 formation is possible using a reversible organometallic synthesis employing catalyzed Al powder, H 2 , and quinuclidine, or another tertiary amine, as an intermediate step. Additionally, many tertiary amines are known to react directly with AlH 3 to form adducts. Previous work indicates that two polymorphs of quinuclidine alane exist, formed using an irreversible process that requires expensive starting materials (e.g. LiAlH 4 ). The conditions of reversible adduct formation are detailed herein, as well as an analysis of quinuclidine alane by Fourier transform infrared spectroscopy and X-ray diffraction.