Oswald Sönke, Seifert Nathan A, Bohle Fabian, Gawrilow Maxim, Grimme Stefan, Jäger Wolfgang, Xu Yunjie, Suhm Martin A
Institut für Physikalische Chemie, Georg-August Universität Göttingen, Tammannstraße 6, 37077, Göttingen, Germany.
Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada.
Angew Chem Int Ed Engl. 2019 Apr 1;58(15):5080-5084. doi: 10.1002/anie.201813881. Epub 2019 Mar 8.
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 , clearly driven by the much stronger hydrogen-bond interaction available to the gauche and even more to the cis monomer units.
1,1,1,3,3,3-六氟-2-丙醇优先聚集成由非手性单体构成的非手性二聚体，但发现三聚体更倾向于由三个亚稳的手性单体单元排列成一个具有张力的OH⋅⋅⋅O氢键环，该环通过次级CH⋅⋅⋅FC相互作用得到加强。这是通过超声速射流膨胀中的红外、微波和拉曼光谱相结合显示出来的，并得到了高水平量子化学计算的支持。它涉及单体的活化能>15 kJ mol ，显然是由gauche构象甚至更多的cis单体单元可获得的更强氢键相互作用驱动的。
