Xe···OCS: Relatively straightforward?

We report a benchmark-quality equilibrium-like structure of the Xe···OCS complex, obtained from microwave spectroscopy. The experiments are supported by a wide array of highly accurate calculations, expanding the analysis to the complexes of He, Ne, Ar, Kr, Xe, and Hg with OCS. We investigate the trends in the structures and binding energies of the complexes. The assumption that the structure of the monomers does not change significantly upon forming a weakly bound complex is also tested. An attempt at reproducing the rm(2) structure of the Xe···OCS complex with correlated wavefunction theory is made, highlighting the importance of relativistic effects, large basis sets, and inclusion of diffuse functions in extrapolation recipes.