Phosphorus–nitrogen compounds. Part 50. Further studies on the formation of bicyclic cyclotetraphosphazatetraene derivatives

Abstract

The reactions of hexachloro-2,6-bis(ethylamino)cyclotetraphosphazatetraene, N₄P₄Cl₆(NHEt)₂, with pyrrolidine, piperidine, morpholine, diethylamine, or cyclopropylamine give bicyclic N₄P₄(NRR′)₅(NHEt)(NEt), as well as monocyclic derivatives N₄P₄(NRR′)₆(NHEt)₂(NRR′= pyrrolidino, piperidino, morpholino, diethylamino, or cyclopropylamino). The reactions of N₄P₄Cl₈ with cyclopropylamine give the bicyclic, N₄P₄(NHC₃H₅)₆(NC₃H₅), and monocyclic, N₄P₄(NHC₃H₅)₈, products, the former being the first structure of its kind with an α-branched alkyl group at the bridgehead to be isolated. Salient features of the ¹H and ³¹P n.m.r. spectra of these bicyclic phosphazenes are discussed and related to their structures. Likely reaction mechanisms are considered.