Synthesis of new azidoalanes with heterocyclic molecular structures

The synthesis of the tetrameric azidoalanes [(CH3)ClAlN3](4) (1) and [(CH3) BrAlN3](4) (2) with heterocyclic cyclooctane-like structures has been demon strated. X-ray structural determinations reveal that 1 and 2 consist of Al4 N4 eight-membered rings in which the Al atoms are bridged by the a nitrogen s of the azide groups. [(CH3)ClAlN3](4) (1) crystallizes in the tetragonal space group P2(1)c with a = 11.077(4), c = 8.662(4), V = 1062.9(8) and Z = 8. [(CH3)BrAlN3](4) (2) crystallizes in the monoclinic space group P2(1) wi th a = 8.6702(12), b = 11.1311(15) c = 11.7501(16), alpha = 90 degrees, bet a = 97.913(2)degrees, gamma = 90 degrees, V = 1123.23(3) (3) and Z = 8. The reaction of AlH3.N(CH3)(3) with HN3 resulted in formation of an azidoalane with composition close to AlH2N3.N(CH3)(3) (3). This compound is unstable with respect to loss of H-2 and N(CH3)(3) at room temperature.