Syntheses and Reactions of the Fluorinated Cyclic Thionylphosphazene NSO(Ar)[NPF<sub>2</sub>]<sub>2</sub> (Ar = 4-t-BuC<sub>6</sub>H<sub>4</sub>−) with Difunctional Reagents EliasAnil J. TwamleyBrendan ShreeveJean'ne M. 2001 The S−aryl substituted thionylphosphazene (Cl<sub>2</sub>PN)<sub>2</sub>[4-t-BuC<sub>6</sub>H<sub>4</sub>(O)SN] (<b>1</b>) was prepared by Friedel−Craft's reaction of NSOCl(NPCl<sub>2</sub>)<sub>2</sub> with <i>tert</i>-butylbenzene. When it reacted with excess KSO<sub>2</sub>F at 110 °C, the P−Cl bonds of <b>1</b> were fluorinated, yielding the tetrafluorothionylphosphazene, (F<sub>2</sub>PN)<sub>2</sub>[4-t-BuC<sub>6</sub>H<sub>4</sub>(O)SN] (<b>2</b>). An equimolar reaction of <b>2 </b>with dilithiated 1,3-propanediol in THF at −78 °C resulted in the formation of the ansa-substituted compound CH<sub>2</sub>(CH<sub>2</sub>O)<sub>2</sub>[FPN]<sub>2</sub>[4-t-BuC<sub>6</sub>H<sub>4</sub>(O)SN] (<b>3</b>). The crystal structures of <b>2</b> and <b>3</b> were determined. In <b>3</b> the ansa ring is trans on the PNS heterocycle with respect to the aryl group. Reaction of <b>2</b> with the disiloxane (CF<sub>2</sub>CH<sub>2</sub>OSiMe<sub>3</sub>)<sub>2</sub>, in the presence of catalytic amounts of CsF in THF at 90 °C, resulted in the formation of the dispiro compound [(CF<sub>2</sub>CH<sub>2</sub>O)<sub>2</sub>PN]<sub>2</sub>[4-t-BuC<sub>6</sub>H<sub>4</sub>(O)SN] (<b>4</b>). Compounds <b>1</b><b>−</b><b>4</b> were characterized by IR, NMR (<sup>1</sup>H, <sup>13</sup>C, <sup>19</sup>F, <sup>31</sup>P), mass spectral, and elemental analyses.