Silicon-based Low Coordinated Phospholes:Synthesis,Structure And Reactivity

Organic phosphine compounds have been widely used in various fields.Among phosphole,due to its unique electronic structure and stereoscopic configuration,can be used as a synthesizer to construct a series of phosphorus derivatives and be applied in many fields.At present,the development of phosphole chemistry is mainly limited by two aspects:one is the lack of synthetic methods for the preparation of phosphole and its derivatives in large quantities;the other is poor stability.These severely restrict the application prospect of the phosphole compounds.Therefore,it is of great significance to develop efficient synthetic route and construct stable novel phosphole.In this thesis,the stability of phosphole was improved by combining the large steric hindrance effect of cyclic silane,especially the characteristic that?electrons can delocalize along the Si-Si bond.A new type of silicon-based low coordinated phosphole with?-?conjugation effect was synthesized by the reaction of chlorosilane and Na OCP.Oxygen anions and phosphorus atoms on the silicon-based low coordination phospholes were used to react with some electrophiles to synthesize stable low coordination phospholes.The content of the thesis mainly includes the following two parts:1. Synthesis of silicon-based low coordinated phospholes:a new type of silicon-based low coordinated phosphole 10 was synthesized by the reaction of cyclopentachlorosilane 9 and Na OCP.The reaction is highly economical,and no organic group is released during the reaction.The structure of phosphole was determined by NMR,single crystal diffraction.Single crystal diffraction showed that the sp² hybrid phosphorus atom and C₂P₂O formed a five-membered ring in a plane,the electrons can delocalize in the five-membered ring.There is also a?-?conjugation effect between cyclopentyl silicon group and phosphole through Si-C bond,the large steric resistance effect of cyclopentyl silicon group,they all make the new silicon-based low coordination phosphole 10 more stable.2. The reactivity of silicon-based low coordinated phospholes:A soft electrophile,iodomethane,is used to react with the phosphorus site of 10 to synthesize silicon-based low coordinated phosphole derivatives 21.A hard electrophile,acetyl chloride,is used to react with the oxygen anion site of phosphole 10 to synthesize silicon-based low coordinated phosphole derivatives 24-26.In this thesis,a new type of silicon-based low coordinated phospholes 10 were synthesized by the reaction of silicon-based cyclopentachlorosilane 9 and Na OCP.The large steric hindrance effect of the cyclopentylsilyl group can effectively improve the stability of phosphole 10.In addition,the?electron effect of the cyclopentylsilyl group also plays a key role in the stability of phosphole 10.At the same time,the reaction of phosphole 10 with electrophile was carried out.According to the theory of hard-soft-acid-base,oxygen anion reacts with hard electrophile and phosphorus atom reacts with soft electrophile,to synthesize phosphole derivatives respectively.