Geometry of a weakly bound complex (H2S, HCN) determined from an investigation of its rotational spectrum

Abstract

The ground-state rotational spectra of 10 isotopic species of a weakly bound complex formed by H₂S and HCN in the gas phase have been investigated by the technique of pulsed-nozzle, Fourier-transform microwave spectroscopy. The following rotational constants, ½(B₀+C₀), centrifugal distortion constants, D_J, and ¹⁴N nuclear quadrupole coupling constants, χ_aa, have been determined: [graphic omitted] Analysis of the constants ½(B₀+C₀) shows that they are consistent only with a geometry of the complex in which the HCN molecule acts as a proton donor in forming a hydrogen bond to the S atom of H₂S. The S, C and N nuclei are collinear (or nearly so), with r(S⋯C)= 3.8088 Å and with the angle ϕ between the S⋯HCN line and the plane of the H₂S subunit equal to 84.5°.