The formation of a novel Lewis acid-base complex between the silyl azide Si(CH3)(3)N-3 and GaCl3 having the formula (H3C)(3)SiN3 . GaCl3 (1) is demonstrated. The X-ray crystal structure of 1 shows that the electron-donating site is the nitrogen atom directly bonded to the organometallic group. Compound 1 crystallizes in the orthorhombic space group Pnma, with cell. dimensions a = 15.823(10) Angstrom, b = 10.010(5) Angstrom, c = 7.403(3) Angstrom, and Z = 4. Low-temperature decomposition of 1 via loss of (H3C)(3)SiCl yields Cl2GaN3 (2), which serves as the first totally inorganic (C,H-free) precursor to heteroepitaxial GaN by ultrahigh-vacuum chemical vapor deposition. A volatile monomeric Lewis acid-base adduct of 2 with trimethylamine, Cl2GaN3 . N(CH3)(3) (3), has also been prepared and utilized to grow high-quality GaN on Si and basal plane sapphire substrates. The valence bond model is used to analyze bond lengths in organometallic azides and related adducts.