Stability and structure of van der Waals complexes between argon and sulfur containing compounds: tetrahydrothiophene–argon

Abstract

The free-jet rotational spectra of the normal and ³⁴S isotopic species of tetrahydrothiophene (THT)–argon have been investigated with either an absorption millimetre-wave or a Fourier-transform microwave spectrometer in the 60–78, and 6–18.5 GHz frequency ranges, respectively. Analysis of the rotational constants has provided two mathematically possible locations for the Ar atom, above or below the ring of THT. The determined distance Ar–CM_THT is R=3.912(8) Å, the Ar–CM_THT–S angle is ϑ=80.1(16)° and the two possible values of the dihedral angle Ar–CM_THT–S–C₄ are φ=69.5(12)° or 98.5(13)°. From the centrifugal distortion constant D_J the dissociation energy of the complex has been estimated to be 2.1 kJ mol^-1.