Tetrel, nonconventional hydrogen bonds, and noticeable role of dispersion in complexes of fluoroform and carbon dichalcogenides

Abstract

Weak noncovalent interactions in complexes between fluoroform and carbon dichalcogenides are explored using highly accurate quantum chemical calculations. Tetrel and hydrogen bonds stabilize these binary systems, with tetrel bonds dominating oxygen-containing complexes and hydrogen bonds prevailing in oxygen-free ones. Distinct characteristics are also found between the two groups in terms of electrostatic contributions. In the former, electrostatics play a secondary role, while in the latter, they are the least attractive term. In all complexes, dispersion interactions predominantly stabilize the most stable structures, with a more pronounced effect in complexes containing heavier chalcogens. The hydrogen bonds in all complexes are purely noncovalent in nature and exhibit blue shifts in the C–H stretching frequency to varying degrees. Detailed analysis of the linear hydrogen bonds in oxygen-containing complexes suggests that the blue shift is a short-range phenomenon, which results from a balance between blue-shift-driving exchange forces and red-shift-driving electrostatic interactions. Meanwhile, dispersion forces are found to exert red-shifting effects.