Axially Chiral, Electrophilic Fluorophosphonium Cations: Synthesis, Lewis Acidity, and Reactivity in the Hydrosilylation of Ketones

Axially chiral [(C6F5)3PF]­[B­(C6F5)4] analogues based on dihydrophosphepines
with a binaphthyl backbone were prepared and structurally characterized
by X-ray diffraction analysis. Computational calculations of FIA and
GEI values attest that these new fluorophosphonium cations have a
higher Lewis acidity compared to the ubiquitous B­(C6F5)3. Furthermore, application of these highly electrophilic
compounds in the catalytic hydrosilylation of ketones and an investigation
of the mechanism lead to a refined picture of the role of highly electrophilic
fluorophosphonium cations.

以联萘为骨架的二氢磷杂环庚烯类轴手性[三(五氟苯基)氟磷鎓][四(五氟苯基)硼酸盐]类似物已被合成，并通过X射线衍射分析完成结构表征。对氟离子亲和能（Fluoride Ion Affinity, FIA）与全局亲电性指数（Global Electrophilicity Index, GEI）的量化计算结果证实，这类新型氟磷鎓阳离子相较于广为使用的三(五氟苯基)硼烷，具有更高的路易斯酸性。此外，将此类高亲电性化合物应用于酮的催化氢化硅烷化反应，并对反应机理展开研究，使我们对高亲电性氟磷鎓阳离子的作用机制有了更为清晰准确的认知。