Primary processes in the photolysis of diazo-n-propane and diazo-n-butane

Abstract

The electronic absorption spectra of diazo-n-propane and diazo-n-butane have been recorded in the gas phase and in cyclohexane solution; the molar extinction coefficients are reported. CNDO/S calculations have allowed the assignment of the band at 2.2 × 10⁴ cm^–1 as an A″â†�A′ transition and the band at 4.4 × 10⁴ cm^–1 as an A′â†�A′. The quantum yield of decomposition upon irradiation in the visible band was unity within experimental error. The quantum yield was pressure and wavelength (within the band) independent. Attempts to detect fluorescence or phosphorescence were unsuccessful, indicating that the emission quantum yields were less than 0.01. Correlation diagrams constructed using diazomethane as a model with the conservation of individual electronic angular momenta explained some of the unusual features of these decomposition reactions and of the electronic spectra.