Three-coordinate main group Lewis acids are exceedingly important reagents in chemical synthesis. In contrast to the well-established chemistries of neutral group 13 and cationic group 14 species, isoelectronic group 15 element dications are unknown. In this work, we use stabilizing N-heterocyclic imine substituents to isolate and characterize phosphorandiylium dications ([R3P]2+) and show that the electrophilicity at the phosphorus atoms is controlled by the π-electron-donating ability of these subtituents. Structural, spectroscopic and theoretical results reveal that the phosphorus dications adopt a perfectly trigonal-planar geometry with the electron-deficient phosphorus centres being well separated from the borate anions. The reactivity of the dications reveal their exceptional Lewis acidity at phosphorus; the adjacent nitrogen atoms, however, are weakly basic, resulting in transformations such as chloride ion abstraction from Me3SiCl and the selective monodefluorination of trifluoromethyl groups.

中文翻译：

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等电子的三配位磷离子的分离，表征和反应性与丙氨酸和甲硅烷基阳离子的关系。

三配位主基路易斯酸在化学合成中是极其重要的试剂。与成熟的中性基团13和阳离子基团14的化学物质相反，等电子基团15的元素指示是未知的。在这项工作中，我们使用稳定的N杂环亚胺取代基来分离和表征磷and鎓离子（[R3P] 2+），并表明磷原子处的亲电性受这些取代基的π电子给体能力控制。结构，光谱和理论结果表明，磷指示剂具有完美的三角平面几何形状，缺电子的磷中心与硼酸根阴离子很好地分开。这些药物的反应性表明它们在磷上具有出色的路易斯酸度。但是，相邻的氮原子