Formation of three-membered phosphorus heterocycles via ligand-exchange reactions in mono-adducts of the phosphenium ion: An ab initio investigation

The formation of ionic three-membered phosphorus heterocycles from unsaturated hydrocarbons and mono-adducts of the phosphenium ion has been investigated using ab initio molecular orbital calculations at the G2 level. In appropriate cases, these so-called exchange reactions are exothermic with no overall barrier, and they should therefore be experimentally feasible. Thus, we suggest that phosphenium ions with one lone-pair donor ligand may represent a valuable new reagent in the synthesis of ionic three-membered phosphorus heterocycles. In addition, we discuss the nature of the electronic interactions in the bis-adducts of the phosphenium ion with two lone-pair donors, two π donors, or with one lone-pair donor and one π donor. (C) 2000 Elsevier Science B.V.