Interaction geometry in the Hexafluoroisopropylalcohol–triflate complex: Structural regulation by a hydrogen-bond anchor and the subordinate role of C–H···O interactions

In this study, the interaction geometry between a hexafluoroisopropylalcohol (HFIP)-containing styrene model and the triflate anion (TfO − ) was investigated using density functional theory (DFT) calculations starting from three distinct initial configurations with slight perturbations. All optimized structures converged to a hydrogen-bond-anchored motif, indicating that the O–H···O interaction of HFIP functions as a primary geometric anchor under the present computational conditions. Aromatic C–H···O contacts were observed only as weak, position-dependent secondary interactions and were not identified as independent stabilization motifs within the present optimization set. Furthermore, neither anion-π interactions nor two-point contact structures were observed as independent interaction geometries. These results suggest that HFIP forms a geometrically constraining hydrogen bond with the anion, which governs the overall interaction geometry. This study highlights geometric feasibility as a first-order criterion for understanding intermolecular interactions.