Vibrational Spectrum and Gas-Phase Structure of Disulfur Dinitride (S2N2)

Gas-phase FTIR spectra of the (6) (B-type) and the (4) (C-type) fundamental bands of S2N2 (D-2h) were recorded with a resolution of 0.004cm(-1) and the vibrational spectrum of S2N2 (D-2h) in solid Ar has been revisited. All IR-active fundamentals and four combination bands were assigned in excellent agreement with calculated values from anharmonic VPT2 and VCI theory based on (explicitly correlated) coupled-cluster surfaces. Accurate experimental vibrational ground- and excited-state rotational constants of (S2N2)-S-32-N-14 are obtained from a rovibrational analysis of the (6) and (4) fundamental bands, and precise zero-point average r(z) (R-z(SN)=1.647694(95)angstrom, (z)(NSN)=91.1125(33)degrees) and semi-experimental equilibrium structures (R-e(SN)=1.64182(33)angstrom, (e)(NSN)=91.0716(93)degrees) of S2N2 have been established. These are compared to the solid-state structure of S2N2 and structural properties of related sulfur nitrogen compounds and to results of ab initio structure calculations.