Angular geometry, binding strength and charge transfer for the complex H2Scenter dot center dot center dot ICl determined by rotational spectroscopy

Ground-state rotational spectra of the isotopomers H2S ... (ICl)-Cl-35, H2S ... (ICl)-Cl-37, HDS ... (ICl)-Cl-35 and D2S ... (ICl)-Cl-35 Of a complex of hydrogen sulphide and iodine monochloride were measured. Rotational cons tants, centrifugal distortion constants, halogen nuclear quadrupole couplin g constants, and I spin-rotation coupling constants were determined. Interp retation of various spectroscopic constants showed that the complex has a g eometry in which the S ... I-Cl nuclei are collinear, with r(S ... I) = 3.1 54(3) Angstrom and the ICl subunit almost perpendicular to the plane of the H2S nuclei [phi = 91.9(12)degrees]. Observed I and Cl nuclear quadrupole c oupling constants are used with a simple model to deduce that intramolecula r charge transfer from S to I is similar to 0.05 e(-). The intermolecular s tretching force constant k(sigma) = 16.6(3) N m(-1). (C) 1999 Elsevier Scie nce B.V. All rights reserved.