Influence of F and Se substitution on the structures, stabilities and nature of the complexes between F2CSe and HOX (X = F, Cl, Br, and I)

Ab initio MP2/aug-cc-pVTZ calculations have been performed to identify local minima on the F2CSe-HOX (X = F, Cl, Br, and I) potential surface for characterizing the types of interactions that stabilize the complexes found at these minima, and to evaluate their relative stabilization. Four types of structures are found for each complex, except for the HOF one. The Se center dot center dot center dot H hydrogen-bonded complexes (I) are accompanied with a secondary X center dot center dot center dot F interaction. The structure II is jointly connected with a tetrel bond and an X center dot center dot center dot Se interaction. The structures III and IV are stabilized by a chalcogen bond and a halogen bond, respectively. The stabilization of I has little dependence on the nature of the X atom, while II, III, and IV become more stable with the increase of the atomic mass of X. The chalcogen-bonded complexes are least stable, the halogen-bonded complexes are more stable than the tetrel-bonded ones, and the hydrogen-bonded complex is weaker than the halogen-bonded one in the HOI complex but stronger in the other complexes. The formation of these interactions has been understood by means of molecular electrostatic potentials and orbital interactions. The electrostatic energy is dominant in the complexes I and IV, although the polarization and dispersion contributions are also important, while the dispersion energy is comparable with the electrostatic contribution in complexes II and III.