Gas phase B(N-3)(3) is readily prepared by a spontaneous room temperature reaction between HN3 and BCl3. The infrared spectrum of the reaction products exhibits strong absorptions at 2163 and 1360 cm(-1) and a weaker absorption near 1100 cm(-1). These features are assigned to B(N-3)(3) by comparison with-results from ab initio calculations of the geometry and vibrational frequencies of the molecule. B(N-3)(3) has a strong UV absorption at 230 nm, with sigma(230) = 1.3 x 10(-17) Cm-2. The density of gaseous B(N-3)(3) prepared in these experiments decays with a time constant near 30 min. This decay is attributed to dissociation at the vessel walls, a process which leaves a visible film. Infrared spectra of films produced by either room temperature dissociation or UV photodissociation of B(N-3)(3) exhibit features attributable to BN, likely in the presence of excess nitrogen.