Photolysis of dimethylcarbamoyl azide in an argon matrix: Spectroscopic identification of dimethylamino isocyanate and 1,1-dimethyldiazene

The UV photolysis of dimethylcarbamoyl azide has been investigated in an argon matrix at cryogenic temperatures. The products of the photolysis were identified by infrared spectroscopy supported by quantum-chemical calculations. Sequential formation of dimethylamino isocyanate (Me₂N-NCO), 1,1-dimethyldiazene (Me₂N=N), and ethane was established. Therefore, the major decomposition channel is identified as Me₂NC(O)N ₃ → Me₂N-NCO → Me₂N=N → Me-Me, via consecutive N₂, CO, and N₂ eliminations. Ground-state geometries, vibrational frequencies, IR intensities, and UV excitation energies of the transient dimethylamino isocyanate and 1,1-dimethyldiazene have been computed using the B3LYP and SAC-CI methods and the aug-cc-pVTZ basis set.