The interaction of phosphavinyl Grignard reagents with group 15 halides: synthesis and structural characterisation of novel heterocyclic and heterocage compounds

Abstract

The reactions of a phosphavinyl Grignard reagent, [CyPC(But)MgCl(OEt2)], Cy = cyclohexyl, with a variety of group 15 halide compounds in a number of stoichiometries have been investigated. When the Grignard reagent is reacted with Ph2PCl or CyPCl2, Cy = cyclohexyl, in a 1∶1 and 2∶1 stoichiometry respectively, the 1,3-diphosphapropene, Ph2PC(But)PCy, and triphosphabicyclo[2.1.0]pentane compound, CyP{C2(But)2P2Cy2}, are formed. The 2∶1 and 3∶1 reactions of the Grignard reagent with either PCl3 or AsCl3 lead to the strained triphospha- and arsadiphosphabicyclo[1.1.1]pentanes, ButC{μ-P(Cy)}2{μ-ECl}CBut, E = P or As in moderate yield. The related 1∶1 reaction of the Grignard reagent with PCl3 affords two products, a phosphino-substituted phosphorus ylide, Cl2PC(But)P(Cy)(Cl)2, and a tetraphosphabicyclo[2.1.1]hexane, ButC{μ-P(Cl)P(Cy)}{μ-P(Cy)}{μ-P(Cl)}CBut, the mechanism of formation of which is discussed. An analogous 1∶1 reaction of the Grignard reagent with SbCl3 led to an unusual heterocyclic compound, (Cl2Sb)(But)CSb(Cl)C(But)P(Cl)(Cy)P(Cy), which quantitatively decomposes in solution to yield the known 1,2-dihydro-1,2-diphosphete, P2(Cy)2C2(But)2. All prepared compounds have been crystallographically characterised.