Synthesis and structures of heterocyclic azidogallanes [(CH3)ClGaN3]4 and [(CH3)BrGaN3]3 en route to [(CH3)HGaN3]x: an inorganic precursor to GaN.

The synthesis of [(CH3)ClGaN3]4 (1) with a heterocyclic cyclooctane-like structure and [(CH3)BrGaN3]3 (2) with a trimeric structure has been demonstrated. X-ray structural determinations reveal that 1 and 2 consist of Ga4N4 eight-membered rings and Ga3N3 six-membered rings, respectively, in which the Ga atoms are bridged by the alpha nitrogens of the azide groups. [(CH3)ClGaN3]4 crystallizes in the tetragonal space group P42(1)c with a = 11.017(4) A, c = 8.699(7) A, and Z = 8. [(CH3)BrGaN3]3 crystallizes in the triclinic space group P1 with a = 8.1080(10) A, b = 9.9390(13) A, c = 10.4439(13) A, alpha = 86.069(3) degrees, beta = 86.771(3) degrees, gamma = 80.829(2) degrees, and Z = 6. The reaction of 1 and 2 with LiGaH4 yields [(CH3)HGaN3]x, which is a new low-temperature source of GaN.