Kato Tsuyoshi, Gornitzka Heinz, Baceiredo Antoine, Schoeller Wolfgang W, Bertrand Guy
Laboratoire d'Hétérochimie Fondamentale et Appliquée, UMR CNRS 5069, Université Paul Sabatier, 118 route de Narbonne, F-31062 Toulouse Cedex 04, France.
J Am Chem Soc. 2002 Mar 20;124(11):2506-12. doi: 10.1021/ja010347h.
Transient diphosphinocarbocations IIP are generated either by addition of phosphenium salts to the stable bis(diisopropylamino)phosphinocarbene or by chloride abstraction from C-phosphino-P-chloro phosphorus ylides. In contrast to their nitrogen anlogues (amidinium salts) IIN, which feature a planar 3-center-4p-electron system, calculations show that IIP should exist as IIPb, in which one phosphorus is planar, while the other remains pyramidal. With small substituents at phosphorus, derivatives of type IIP rearrange by a 1,3-shift of a phosphorus substituent to the other phosphorus center to give C-phosphoniophosphaalkenes. When bulky substituents are present at phosphorus, derivatives IIP undergo ring closure, giving rise to the corresponding cyclic valence isomers IIIP, in which the carbon atom bears a negative charge. Diphosphinocarbocations IIP can be trapped by acetonitrile giving regioselectively the corresponding [2+3] cycloadduct.
瞬态二膦基碳正离子IIP可通过以下两种方式生成：将鏻盐加成到稳定的[双（二异丙基氨基）膦基]（硅基）卡宾上，或从C-膦基-P-氯磷叶立德中脱去氯。与具有平面3中心-4p电子体系的氮类似物（脒盐）IIN不同，计算表明IIP应以IIPb的形式存在，其中一个磷是平面的，而另一个保持金字塔形。当磷上有小取代基时，IIP型衍生物通过磷取代基向另一个磷中心的1,3-迁移而重排，生成C-膦鎓磷亚烯。当磷上存在大体积取代基时，IIP衍生物发生闭环反应，生成相应的环状价异构体IIIP，其中碳原子带有负电荷。二膦基碳正离子IIP可被乙腈捕获，区域选择性地生成相应的[2+3]环加成物。
