Microwave rotational spectrum of a weakly bound complex formed by hydrogen sulphide and hydrogen chloride

Abstract

A weakly bound dimer formed by hydrogen sulphide and hydrogen chloride has been identified in the gas phase by means of its rotational spectrum which has been detected with the aid of the sensitive technique of pulsed-nozzle, Fourier-transform microwave spectroscopy. The spectra of eight isotopic species have been analysed to give rotational constants (B₀+C₀), centrifugal distortion constants D_J and Cl nuclear quadrupole coupling constants X_aa as follows: [graphic omitted]

The listed spectroscopic constants allow us to establish that the weak intermolecular linkage occurs through a hydrogen bond, with HCl acting as the proton donor and the S atom acting as the proton acceptor. The S⋯H—Cl nuclei are collinear (or nearly so) with r(S⋯Cl)= 3.8092 Å, and the plane of the H₂S molecule is almost perpendicular (ϕ= 93.8°) to the line of the hydrogen bond. Conclusions about the relative strength of the hydrogen bond are drawn from analyses of the constants D_J and X_aa.