The Chiral Trimer and a Metastable Chiral Dimer of Achiral Hexafluoroisopropanol: A Multi‐Messenger Study. Issue 15 (8th March 2019)

• Record Type: Journal Article
• Authors: Oswald, Sönke; Seifert, Nathan A.; Bohle, Fabian; Gawrilow, Maxim; Grimme, Stefan; Jäger, Wolfgang; Xu, Yunjie; Suhm, Martin A.
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 15(2019)
• Page Start: 5080
• Page End: 5084
• Publication Date: 2019-03-08
• Subjects: chirality synchronization -- experimental benchmarking -- fluorous interactions -- hydrogen bonds -- supersonic jets; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201813881
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: 1, 1, 1, 3, 3, 3‐hexafluoro‐propan‐2‐ol aggregates preferentially into an achiral dimer of achiral monomers, but the trimer is found to prefer three metastable chiral monomer units arranged into a strained OH⋅⋅⋅O hydrogen‐bonded ring, which is reinforced by secondary CH⋅⋅⋅FC interactions. This is shown by a combination of infrared, microwave, and Raman spectroscopy in supersonic jet expansions and supported by high‐level quantum chemical calculations. It involves an activation of the monomers by >15 kJ mol −1, clearly driven by the much stronger hydrogen‐bond interaction available to the gauche and even more to the cis monomer units. Abstract : When does chirality set in? Hexafluoroisopropanol prefers mirror symmetry when isolated or dimerized at low temperatures. By probing dipoles, dipole derivatives, and polarizability derivatives in supersonic jet experiments and computations, it is shown that the most stable trimer only contains chiral constituents.