A theoretical study of the formation of stable anion intermediates via electron capture by heterosubstituted three membered ring XCH 2CY 2 compounds ( X = O, S, NH, PH; Y = H, F)

Abstract

A comparison has been made between the electron acceptor properties of various three membered ring molecules, XCH 2CY 2 (X = O, NH, S, PH; Y = H, F). In a first step, the emphasis has been put on the ability of these substrates to accommodate an extra electron in their lowest-lying antibonding (valence and diffuse) MOs (vertical anions). A strong dichotomy was found between compounds bearing a heteroatom of the second row and those bearing a heteroatom of the third row. For the second row heteroatoms, the electron was essentially located in the diffuse space attached to the H atoms, via the XH (σ ∗) and CH 2 (π ∗) antibonding MOs; while for first row ones, it remained mainly located on the heteroatom, in a Rydberg + valence p-type MO. The open anions resulting from ring opening have then been studied. Two series of anions resulted: when F-substituents were present on the terminal carbon atom, a 1–3 dipolar structure was obtained, whereas the possibility of resonant forms was present when F-substituents were borne by the central C atom. The possibility of obtaining stable anionic species has finally been qualitatively examined.