The reaction of (Mes*AlH2)(2) (Mes* = -C6H2-2,4,6-t-Bu-3) with HN(SiMe3)(2) affords the monomeric amidoarylalane Mes*Al(H)N(SiMe3)(2), 1. This product can also be synthesized by the reaction of [Mes*AlH2](2) with LiN(SiMe3)(2), which, in addition, yields the by products LiAlH2{N(SiMe3)(2)}(2), 3, and Mes*H. Thermolysis of 1 at 175-180 degrees C affords three different products : Mes*AlC6H2-2,4-t-Bu-2-6-CMe2CH2, 2, the related species (Me3Si)(2)NAlC6H2- 2,4-t-Bu-2-6-CMe2CH2, 4, and the imide [Mes*AlN(SiMe3)](n), 5. In addition, the previously reported monomeric alane Mes*2AlH was synthesized in ca. 70% yield by a one-pot reaction between LiMes* (generated in situ) and AlH3 . NMe3. All products were spectroscopically characterized, and the structure of 1 was determined by X-ray crystallography. The Al-N distance (1.819(2) Angstrom) in 1 is relatively long. However, it has a substantial, 18.5 kcal mol(-1), Al-N rotation barrier which is attributed to steric congestion rather than Al-N pi bonding.