Matrix isolation spectroscopic study of the free radical HCCN

The free radical HCCN was produced in an Ar matrix via photolysis of its precursor diazoacetonitrile, NNCHCN, with radiation of wavelengths longer than 350 nm. The ir spectra of HCCN and three isotopic modifications (DCCN, HC13CN, and HCC15N) were obtained, and normal coordinate analyses based on two different geometries, bent and linear, were carried out. The results provide a determination of the general valence force field, and favor the linear, allenic configuration H–Ċ=C=Ṅ. The electronic spectrum of HCCN in an argon matrix was also obtained. A tentative assignment of the band system observed in the uv part of the spectrum has been made.