Intramolecular Si⋅⋅⋅O Tetrel Bonding: Tuning of Substituents and Cooperativity

A computational study of an intramolecular tetrel bond in o‐methoxymethyl‐PhSiF 3 (P) and its derivatives at the 4 and 5 positions by substituents X (4‐X−P and 5‐X−P, X=F, Cl, Br, NO 2 , OH, and NH 2 ) has been performed. The Si⋅⋅⋅O interaction is characterized by the short Si⋅⋅⋅O distance, strong orbital interaction, large interaction energy, and negative energy density. Substituents do not greatly affect the strength of the intramolecular Si⋅⋅⋅O interaction but some interesting results are obtained. The electron‐donating group in 5‐OH−P strengthens this interaction more than the electron‐withdrawing group in 5‐NO 2 ‐P. The interaction energy of the intramolecular Si⋅⋅⋅O interaction has been computed with three different methods and the most reliable result is obtained with an expression using the potential energy density at the Si⋅⋅⋅O bond critical point. When a water molecule is attached to P to form an OH⋅⋅⋅F hydrogen bond, the intramolecular Si⋅⋅⋅O interaction is greatly enhanced yielding an interaction energy up to ∼12 kcal mol −1 .