Synthesis and Characterization of Carbonyl Diazide, OC(N<sub>3</sub>)<sub>2</sub>

The previously recognized “extremely explosive” carbonyl diazide, OC(N<sub>3</sub>)<sub>2</sub>, 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% <i>anti</i>−<i>syn</i> versus 88% <i>syn</i>−<i>syn</i> conformer in the gaseous equilibrium mixture at room temperature was estimated by matrix IR spectroscopy. In the crystal structure, only the more stable <i>syn</i>−<i>syn</i> conformer was observed. The preference of the <i>syn</i>−<i>syn</i> configuration was supported by DFT calculations.