Condensed and Multi-Ring Phosphazenes

The compound PgN7Cl9 is one of the minor products obtainable from the reaction between PCI5 and NH4CI (7.365a). Crystal structure analysis has established that this compound has C3v synunetry with an almost coplanar arrangement of the central N atom and the three P atoms to which it is attached. The central P-N bonds are longer than the peripheral. 

When trimeric chloride is reacted with diphenyl magnesium in dioxane solution, the products include the centrosymmetrical compound (7.365b). Alkyl derivatives of the latter can be made by condensation reaction. 

If geminal diaminotetrachlorophosphazene is reacted with phosphorus pentachloride and then treated with bis(trimethylsilyl)methylamine, ring closure occurs and a spiran compound is produced according to scheme (7.367) (Table 7.7). 

Trans non-gem P4N4Cl( (NHEt)2 reacts with excess dimethylamine in chloroform to give a bicyclic phosphazene (7.369). Another bicyclic derivative can be made by reaction (7.370) using a tetrameric azide. 

A spiran phosphazene can be obtained by reaction (7.371) [27] and two phosphazene rings linked by an O atom result from reaction (7.372). 

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