Matrix isolation and EPR spectroscopy of septet 3,5-difluoropyridyl-2,4,6-trinitrene

Septet 3,5-difluoropyridyl-2,4,6-trinitrene along with quintet 2-azido-3,5-difluoropyridyl-4,6-dinitrene, quintet 4-azido-3,5-difluoropyridyl-2,6-dinitrene, triplet 2,6-diazido-3,5-difluoropyridyl-4-nitrene, and triplet 2,4-diazido-3,5-difluoropyridyl-6-nitrene have been obtained by photolysis of 2,4,6-triazido-3,5-difluoropyridine in solid argon at 4 K. The electronic and magnetic properties of the matrix-isolated nitrenes were studied using electron paramagnetic resonance (EPR) spectroscopy in combination with density functional theory (DFT) calculations. The fine-structure parameters of the nitrenes were determined with high accuracy from computer spectral simulations. All signals in the EPR spectra of the nitrenes randomly oriented in the solid phase were unambiguously assigned on the basis of eigenfield calculations of the Zeeman energy levels and angular dependencies of resonance fields from the direction of the applied magnetic field.