Difluorinated Cyclohexanes: Energetics and Intra- and Intermolecular Interactions.

Abstract

Fluorinated cyclohexanes are essential building blocks for high-performance molecules, including ion carriers and liquid crystals. This quantum-chemical study evaluates the relative energies of all difluorinated cyclohexane isomers, highlighting key intramolecular interactions as thermodynamic modulators. The stability of 1,1-difluorocyclohexane arises from an anomeric-like n_F → σ*_CF interaction, despite FCF repulsion. Dipolar repulsion between CF bonds affects isomers like diequatorial trans-1,2 and diaxial cis-1,3, while axial CH···CF electrostatic attraction stabilizes trans-1,3 and diaxial trans-1,4 isomers. Hyperconjugation involving antiperiplanar CH and CF bonds also contributes. Notably, diaxial CF bonds facilitate self-assembly via interactions between negatively charged fluorines and positively charged hydrogens. This study advances understanding of fluorinated cyclohexanes' thermodynamic behavior, providing a framework for designing tailored fluorinated compounds for advanced applications.