Vibrational spectrum and gas-phase structure of disulfur dinitride (S2N2)

Gas-phase FTIR spectra of the ν6 (B-type) and the ν4 (C-type) fundamental bands of S2 N2 (D2h ) were recorded with a resolution of ≤0.004 cm(-1) and the vibrational spectrum of S2 N2 (D2h ) 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 (32) S2 (14) N2 are obtained from a rovibrational analysis of the ν6 and ν4 fundamental bands, and precise zero-point average rz (Rz (SN)=1.647694(95) Å, αz (NSN)=91.1125(33)°) and semi-experimental equilibrium structures (Re (SN)=1.64182(33) Å, αe (NSN)=91.0716(93)°) of S2 N2 have been established. These are compared to the solid-state structure of S2 N2 and structural properties of related sulfur nitrogen compounds and to results of ab initio structure calculations.