A New Route to Alkali Metal Aluminum Hydrides Maih4with M = Na, K, Rb, Cs and Structural Features for the Whole Family with M = Li TO Cs

Abstract
MAIH4 with M=Na, K, Rb and Cs were prepared in toluene or hexane from an exchange reaction between LiAIH4 and an halide of the corresponding metal dissolved in the medium as a Ziegler-type complex with triethylaluminum. The best process involves the equimolar complexes MF-AIEt3 with fluorides. The four MAIH4 were quantitatively obtained with a purity > 99% (wt). RbAIH4 and CsAIH4 have the same barite-type structure as KAIH4 (orthorhombic, Z=4), with parameters (Å, ±.002) a:b:c: 9.253:5.950:7.599; 9.981:6.075:7.953, respectively.