Cyanogen Azide Research Articles

Matrix-Isolation Study of the Photolysis of Cyanogen Azide. II. The Symmetric Stretching Fundamental of the Free Radical NCN

The photolysis of Ar:N3CN samples at 14°K with the full light of a cadmium arc has been found to permit complete conversion of the cyanogen azide to the free radical NCN, plus molecular nitrogen. At the high concentration of NCN thus achieved, a weak absorption appears at 2672 cm−1. The photolytic behavior of this feature and its shifts upon isotopic substitution support its assignment as the combination band (ν1+ν3) of NCN, permitting deduction of a value of 1197 cm−1 for ν1 of this species. The thermodynamic properties of NCN have been revised in accord with this assignment. The carbon—nitrogen stretching force constant approaches a value characteristic of a doubly bonded species, and the stretching interaction constant is relatively large and positive. Cyanogen azide photolyzes in both its 2750- and its 2200-Å absorption regions to produce NCN+N2. However, NCN itself photolyzes when subjected to radiation near 2500 Å, producing carbon atoms in the 3P state, which, in turn, may react with N2 to form the free radical CNN.

Matrix-Isolation Study of the Infrared and Ultraviolet Spectra of the Free Radical CNN

Features appearing at 393, 1241, and 2847 cm−1 after photolysis of matrix-isolated cyanogen azide with 2100–2800-Å radiation are shown to exhibit parallel behavior. Isotopic data are consistent with the assignment of these three features as fundamentals of the free radical CNN, produced by the reaction of carbon atoms with molecular nitrogen. Ultraviolet absorptions at 4189 and 3964 Å can also be assigned to CNN. The force constants and thermodynamic properties of CNN have been derived. The carbon—nitrogen bond is found to have approximately triple-bond character and the nitrogen—nitrogen bond approximately double-bond character.

Singlet and Triplet States of NCN in the Flash Photolysis of Cyanogen Azide

Singlet and Triplet States of NCN in the Flash Photolysis of Cyanogen Azide

Matrix-Isolation Infrared Spectrum of the Free Radical CCO

The photolysis of matrix-isolated cyanogen azide in the presence of carbon monoxide at wavelengths shorter than 2800 Å has been found to lead to the appearance of the free radical CCO in concentration sufficient for direct spectroscopic observation. This species has also been produced by the vacuum ultraviolet photolysis of matrix-isolated carbon suboxide. The three vibrational fundamentals of CCO have been observed in an argon matrix at 381, 1074, and 1978 cm−1, and CCO has been found to have a continuum near 5000 Å. Isotopic studies are consistent with a linear structure for CCO. Estimates of the force constants and thermodynamic properties are given. CCO has been observed to react with CO with little or no activation energy to form carbon suboxide. Other reactions occurring in the matrix are also discussed.

Matrix Isolation Study of the Photolysis of Cyanogen Azide. The Infrared and Ultraviolet Spectra of the Free Radical NCN

The infrared and ultraviolet absorption spectra of the free radical NCN have been observed following photolysis at wavelengths longer than 2800 Å of cyanogen azide isolated in argon, nitrogen, carbon monoxide, and carbon dioxide matrices. The infrared-active vibrational fundamentals of NCN appear at 423 and at 1475 cm−1. Isotopic studies are consistent with this identification. The force constants and thermodynamic properties of NCN have been estimated. Two ultraviolet absorption systems are associated with NCN. The first of these, previously reported, lies near 3290 Å. The second system is comprised of a progression of bands spaced at intervals of approximately 1045 cm−1, lying between 3000 and 2400 Å. The nature of this second transition is discussed. At wavelengths longer than 2800 Å both cyanogen azide and NCN have been found to photolyze with the production of carbon atoms. The nature of the new features observed in the infrared and ultraviolet spectral regions after photolysis with short-wavelength radiation is considered.

Formation of the NCN Radical During the Flash Photolysis of Cyanogen Azide

Formation of the NCN Radical During the Flash Photolysis of Cyanogen Azide