Prominent enhancing effects of substituents on the strength of π...σ-hole tetrel bond

The potential applications of tetrel bonds involving p-molecules in crystal materials and biological systems have prompted a theoretical investigation of the strength of pi...sigma-hole tetrel bond in the systems with acetylene and its derivatives of CH3, AuPH3, Li, and Na as well as benzene as the pi electron donors. A weak tetrel bond (Delta E < 15 kJ/mol) is found between acetylene and tetrel donor molecule TH3F (T = C, Si, Ge, Sn, and Pb). All substituents strengthen the pi tetrel bond, but the electron-donating sodium atoms have the largest enhancing effect and the interaction energy is up to about 24 kJ/mol in C2Na2-CH3F. The electron-donating ability of the AuPH3 fragment is intermediate between the methyl group and alkali metal atom. The origin of the stability of the pi tetrel-bonded complex is dependent on the nature of the tetrel donor and acceptor molecules and can be regulated by the substituents.