Chalcogen bonding between tetravalent SF4 and amines

Area of Science:

• Computational chemistry
• Supramolecular chemistry
• Chemical bonding

Background:

• Chalcogen bonds are increasingly recognized non-covalent interactions.
• Sulfur tetrafluoride (SF4) is a versatile Lewis acid capable of forming unique interactions.

Purpose of the Study:

• To investigate the N···S chalcogen bond between SF4 and various alkyl and arylamines.
• To quantify the strength and nature of this interaction using computational methods.

Main Methods:

• Ab initio calculations were employed to model the interaction.
• Analysis of binding energies, charge transfer, and electrostatic potentials was performed.

Main Results:

• A strong N···S chalcogen bond was observed, with binding energies ranging from 7 to 14 kcal/mol.
• Charge transfer from the nitrogen lone pair to SF4's antibonding orbitals is a key stabilizing factor.
• Induction energy significantly contributes to the overall attraction, exceeding 50% of the total interaction energy.

Conclusions:

• The N···S chalcogen bond in SF4-amine complexes is robust and primarily driven by electrostatic and charge-transfer contributions.
• The interaction strength is not solely predicted by the electrostatic potential of the amines.
• The observed bond characteristics suggest a potential for weak covalent character in these systems.