Far-Infrared Spectrum of S(CN)₂ Measured with Synchrotron Radiation: Global Analysis of the Available High-Resolution Spectroscopic Data

The high resolution Fourier transform spectrum of the chemically challenging sulfur dicyanide, S­(CN)2, molecule was recorded at the far-infrared beamline of the synchrotron at the Canadian Light Source. The spectrum covered 50–350 cm–1, and transitions in three fundamentals, ν4, ν7, and ν8, as well as in the hot-band sequence (n + 1)­ν4 – nν4, n = 1–4, have been assigned and measured. Global analysis of over 21 300 pure rotation and rotation vibration transitions allowed determination of precise energies for 12 of the lowest vibrationally excited states of S­(CN)2, including the five lowest fundamentals. These results constitute an extensive set of benchmarks for ab initio anharmonic force field calculations and the observed and calculated vibration–rotation constants and anharmonic frequencies are compared. The semiexperimental equilibrium, reSE, geometry of S­(CN)2 has also been evaluated. In the course of the measurements, new information concerning the physical chemistry of S­(CN)2 has been obtained.