Syntheses and Reactions of the Fluorinated Cyclic Thionylphosphazene NSO(Ar)[NPF₂]₂ (Ar = 4-t-BuC₆H₄−) with Difunctional Reagents

The S−aryl substituted thionylphosphazene (Cl₂PN)₂[4-t-BuC₆H₄(O)SN] (1) was prepared by Friedel−Craft's reaction of NSOCl(NPCl₂)₂ with tert-butylbenzene. When it reacted with excess KSO₂F at 110 °C, the P−Cl bonds of 1 were fluorinated, yielding the tetrafluorothionylphosphazene, (F₂PN)₂[4-t-BuC₆H₄(O)SN] (2). An equimolar reaction of 2 with dilithiated 1,3-propanediol in THF at −78 °C resulted in the formation of the ansa-substituted compound CH₂(CH₂O)₂[FPN]₂[4-t-BuC₆H₄(O)SN] (3). The crystal structures of 2 and 3 were determined. In 3 the ansa ring is trans on the PNS heterocycle with respect to the aryl group. Reaction of 2 with the disiloxane (CF₂CH₂OSiMe₃)₂, in the presence of catalytic amounts of CsF in THF at 90 °C, resulted in the formation of the dispiro compound [(CF₂CH₂O)₂PN]₂[4-t-BuC₆H₄(O)SN] (4). Compounds 1−4 were characterized by IR, NMR (¹H, ¹³C, ¹⁹F, ³¹P), mass spectral, and elemental analyses.