Cooperative effects between tetrel bond and other s- hole bond interactions: a comparative investigation

Covalently bonded atoms of Groups IV- VII tend to have anisotropic charge distributions, the electronic densities being less on the extensions of the bonds ( sigma- holes) than in the intervening regions. These sigma- holes often give rise to positive electrostatic potentials through which the atom can interact attractively and highly directionally with negative sites. In this work, cooperative effects between tetrel bond and halogen/ chalcogen/ pnicogen bond interactions are studied in multicomponent YH3M center dot center dot center dot NCX center dot center dot center dot NH3 complexes, where Y = F, CN; M = C, Si and X = Cl, SH and PH2. These effects are analysed in detail in terms of the structural, energetic, charge- transfer and electron density properties of the complexes. The nature of the sigma- hole bonds is unveiled by quantum theory of atoms in molecules and natural bond orbital theory. A favourable cooperativity is found with values that range between - 0.34 and - 1.15 kcal/ mol. Many- body decomposition of interaction energies indicate that two- body energy term is the most important source of the attraction, which its contribution accounts for 87%- 96% of the total interaction energy.