Vibrational Spectra and Structure of S4N4 and S2N2

The infrared spectrum of solid S4N4 has been recorded to a low-frequency limit of 50 cm−1, the Raman spectrum re-examined, and depolarization ratios of the most intense spectral lines obtained. The 12 observed vibrational fundamentals of tetrasulfur tetranitride have been fit by means of a valence force field in which 10 independent parameters were adjusted. The calculated frequencies are in good agreement with the experimental data and a complete vibrational assignment is proposed based in part on the results of the computations. A discussion of the computed potential field in relation to the molecular structure of S4N4 is included. The infrared spectrum of solid S2N2 at − 80°C has been obtained to a low-frequency limit of 50 cm−1. Five vibrational frequencies have been observed. The molecule was subjected to vibrational analysis based on D2h symmetry. The results of the computations were used in assigning five vibrational fundamentals.