CH3N=SF2=NCH3: Structural, Conformational, and Configurational Properties in the Gaseous and in the Condensed Phases

Abstract

CH3N=SF2=NCH3 (1) was obtained in 88% yield from the reaction of a bis(silylated) amine RN(SiMe3)2 with a sulfur tetrafluoride imide RN=SF4 (R = R = CH3). Single crystals suitable for X-ray crystallography were obtained by low-temperature crystallization; the data were collected at 120 K. Compound 1 crystallizes in the monoclinic space group P21/c with a = 5.8356(7) Å, b = 12.1665(14) Å, c = 8.1488(8) Å, Beta = 110.381(7)°, Z = 4, in the anti-anti form (whereby anti or syn describe the orientation of the N-CH3 bonds with respect to opposite S=N bonds). The structural, conformational, and configurational properties of CH3N=SF2=NCH3 were studied by vibrational spectroscopy [IR (gas) and Raman (liquid)] and quantum chemical calculations [B3LYP and MP2 with 6-311+G(2df,p) and cc-pVTZ basis sets]. Vibrational spectroscopy in the gas and liquid phases shows evidence of a configurational equilibrium of the anti-anti form and a slightly less favored anti-syn form of CH3N=SF2=NCH3.