Synthesis of N-aryl-substituted iminophosphoranes and NMR spectroscopic investigation of their acid–base properties in acetonitrile

Abstract

A series of RNP(Pyrr)₃ iminophosphoranes (P₁ phosphazenes), where R is amino-, α-naphthyl- or substituted phenyl group, is prepared by the Kirsanov reaction and characterized by FT NMR and other properties. The ΔpK_a-values of the 12 different synthesized phosphazenes and C₆H₅NP(NMe₂)₃ are determined in acetonitrile relative to the reference bases using ¹³C NMR spectroscopy. The obtained pK_a-values are compared with the corresponding values of RNH₂ amines. The pK_a-values of the synthesized phosphazenes in acetonitrile range from 14.6 to 26.8 pK_a units.