Effect of superalkali substituents on the strengths and properties of hydrogen and halogen bonds

Quantum chemical calculations have been performed for the complexes Li3OCCX–Y (X = Cl, Br, H; Y = NH3, H2O, H2S) and Li3OCN–X′Y′ (X′Y′ = ClF, BrCl, BrF, HF) to study the role of superalkalis in hydrogen and halogen bonds. The results show that the presence of an Li3O cluster in a Lewis acid weakens its acidity, while its presence in a Lewis base enhances its basicity. Furthermore, the latter effect is more prominent than the former one, and the presence of an Na3O cluster causes an even greater effect than Li3O. The strengths of hydrogen and halogen bonds were analyzed using molecular electrostatic potentials. The contributions of superalkalis to the strength of hydrogen and halogen bonds were elucidated by analyzing differences in electron density.