Layered crystal structure, conformational and vibrational properties of 2,2,2-trichloroethoxysulfonamide: an experimental and theoretical study.

The molecular structure of 2,2,2-trichloroethoxysulfonamide, CCl3CH2OSO2NH2, has been determined in the solid state by X-ray diffraction data and in the gas phase by ab initio (MP2) and DFT calculations. The substance crystallizes in the monoclinic P21/c space group with a = 9.969(3)Å, b = 22.914(6)Å, c = 7.349(2)Å, β = 91.06(3)°, and Z = 8 molecules per unit cell. There are two independent, but closely related molecular conformers in the crystal asymmetric unit. They only differ in the angular orientation of the sulfonamide (SO2NH2) group. The conformers are arranged in the lattice as center-symmetric NH · · · O(sulf)-bonded dimers. Neighboring dimers are linked through further NH · · · O(sulf) bonds giving rise to a crystal layered structure. The solid state infrared and Raman spectra have been recorded and the observed bands assigned to the molecular vibration modes. Also, the thermal behavior of the substance was investigated by TG-DT analysis. The stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond (NBO) analysis.