Synthesis and Characterization of Carbonyl Diazide, OC(N₃)₂

The previously recognized “extremely explosive” carbonyl diazide, OC(N₃)₂, was prepared as a pure compound and unambiguously characterized by gas-phase IR, matrix IR, and Raman spectroscopy and X-ray crystallography for the first time. The pure substance shows remarkable kinetic stability at room temperature in the gaseous, liquid, and solid states. A melting point of 16 °C and vapor pressure of 5.6 mbar at 0 °C were determined. Two planar conformers were found in the gas phase, and a composition of 12% anti−syn versus 88% syn−syn conformer in the gaseous equilibrium mixture at room temperature was estimated by matrix IR spectroscopy. In the crystal structure, only the more stable syn−syn conformer was observed. The preference of the syn−syn configuration was supported by DFT calculations.