An ab initio investigation of chalcogen-hydride interactions involving HXeH as a chalcogen bond acceptor

This work presents an ab initio study on chalcogen-hydride interactions in several binary complexes of chalcogen-containing molecules with HXeH. The geometries, H-Xe stretching frequencies and interaction energies of XCY center dot center dot center dot HXeH binary complexes are investigated at MP2/aug-cc-pVTZ and CCSD(T)/aug-cc-pVTZ levels of theory, where X = O, S, Se, Te and Y = S, Se, Te. For each XCY center dot center dot center dot HXeH complex, a chalcogen-hydride bond is formed between the negatively charged hydrogen atom of the HXeH molecule and the most positive electrostatic potential region (sigma-hole) on the surface of the interacting atom Y. Upon complex formation, a notable blue shift is found for the H-Xe stretch vibration. This result reveals that there is a stronger H-(XeH)(+) ion-pair character in XCY center dot center dot center dot HXeH complexes than in free HXeH molecule. In order to shed light on the origin of the chalcogen-hydride interactions, molecular electrostatic potential, quantum theory of atoms in molecules and interaction energy decomposition analyses are performed. Cooperative effects between a conventional chalcogen bond and the chalcogen-hydride interaction in OCY center dot center dot center dot OCY center dot center dot center dot HXeH complexes are also investigated.