An Ab Initio Investigation of the Geometries and Binding Strengths of Tetrel-, Pnictogen-, and Chalcogen-Bonded Complexes of CO(2), N(2)O, and CS(2) with Simple Lewis Bases: Some Generalizations

Geometries, equilibrium dissociation energies (D(e)), and intermolecular stretching, quadratic force constants (k(σ)) are presented for the complexes B⋯CO(2), B⋯N(2)O, and B⋯CS(2), where B is one of the following Lewis bases: CO, HCCH, H(2)S, HCN, H(2)O, PH(3), and NH(3). The geometries and force constants were calculated at the CCSD(T)/aug-cc-pVTZ level of theory, while generation of D(e) employed the CCSD(T)/CBS complete basis-set extrapolation. The non-covalent, intermolecular bond in the B⋯CO(2) complexes involves the interaction of the electrophilic region around the C atom of CO(2) (as revealed by the molecular electrostatic surface potential (MESP) of CO(2)) with non-bonding or π-bonding electron pairs of B. The conclusions for the B⋯N(2)O series are similar, but with small geometrical distortions that can be rationalized in terms of secondary interactions. The B⋯CS(2) series exhibits a different type of geometry that can be interpreted in terms of the interaction of the electrophilic region near one of the S atoms and centered on the C(∞) axis of CS(2) (as revealed by the MESP) with the n-pairs or π-pairs of B. The tetrel, pnictogen, and chalcogen bonds so established in B⋯CO(2), B⋯N(2)O, and B⋯CS(2), respectively, are rationalized in terms of some simple, electrostatically based rules previously enunciated for hydrogen- and halogen-bonded complexes, B⋯HX and B⋯XY. It is also shown that the dissociation energy D(e) is directly proportional to the force constant k(σ), with a constant of proportionality identical within experimental error to that found previously for many B⋯HX and B⋯XY complexes.