Preparative and nuclear magnetic resonance studies of diazadiphosphetidines. Part VI. 2,4-Dialkyl-2,2,4,4-tetrafluoro-,3-dimethyl-1,3,2,4-diazadiphosphetidines

Abstract

Proton-decoupled ¹⁹F and ³¹P n.m.r. spectra of a series of dialkyltetrafluorodiazadiphosphetidines. (RF₂PNMe)₂(I; R = Me, Et, Prⁱ, or Bu^t), have been recorded and analysed for temperatures high enough for gauche⇌trans exchange to be rapid on the n.m.r.timescale, and at low temperatures when the exchange is slow. Some ¹H n.m.r. data are also given, including the results of a comoplete analysis of the spectrum of (I; R = Me) on an [A(X)₂M₃]₂ basis. Many signs of coupling constants have been obtained either from the spectral analysis or from double resonance experiments. The coupling constants and chemical shifts are compared and discussed. There is a very large isomer effect on ²J_PP, especially for the Bu^t compound. Isomer populations have been obtained by several methods. The preparations of the Prⁱ and Bu^t compounds, not previously reported, are described in detail.