Isolation, characterization and reactivity of three-coordinate phosphorus dications isoelectronic to alanes and silylium cations
Isolation, characterization and reactivity of three-coordinate phosphorus dications isoelectronic to alanes and silylium cations
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DOI：
10.1038/s41557-019-0348-0
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发表时间：
2019-12-01
期刊：
影响因子：
21.8
通讯作者：
Dielmann, Fabian
中科院分区：
文献类型：
--
作者：
Mehlmann, Paul;Witteler, Tim;Dielmann, Fabian
三配位主族刘易斯酸是化学合成中非常重要的试剂。与中性第13族和阳离子第14族物质的成熟化学相比，等电子第15族元素的双价态是未知的。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二亚胺双阳离子（[R3 P]（2+）），并表明磷原子处的亲电性由这些取代基的π-供电子能力控制。结构，光谱和理论的结果表明，磷dications采用一个完美的三角平面几何与缺电子的磷中心被很好地从硼酸根阴离子分离。双阳离子的反应性揭示了它们在磷上的特殊刘易斯酸性;然而，相邻的氮原子是弱碱性的，导致了诸如从Me 3SiCl中提取氯离子和选择性地单脱三氟甲基基团的转化。
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 pi-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.