Synthesis and structural characterization of the first examples of butadiynyl derived cyclic fluorinated phosphazenes

• First examples of butadiyne derived fluorinated cyclophosphazenes.
• Both mono and geminally disubstituted products obtained.
• Geminal compounds with both alkyne and butadiyne units also synthesized.
• Structural studies indicate unprecedented stacking of P3N3F5 units.

The first examples of butadiyne derived cyclic fluorophosphazenes have been synthesized and structurally characterized. A reaction of PhCCCCLi with P3N3F6 yielded the phenylbutadiyne monosubstituted fluorophosphazene, [PhCCCC(F)PN](PNF2)2 (1) along with the geminally disubstituted fluorophosphazene [(PhCCCC)2PN](PNF2)2 (2), while an analogous reaction of FcCCCCLi (Fc = ferrocenyl) with N3P3F6 gave the ferrocenylbutiadiyne monosubstituted fluorophosphazene, [FcCCCC(F)PN](PNF2)2 (3) and the geminally disubstituted fluorophosphazene [(FcCCCC)2PN](PNF2)2 (4). Compound 1 on reaction with FcCCLi yielded the unsymmetrical geminally disubstituted compound [(FcCC)(PhCCCC)PN](F2PN)2 (5). Reactions of compound 3 with PhCCLi and FcCCLi, also resulted in unsymmetrically disubstituted fluorophosphazenes [(PhCC)(FcCCCC)PN](F2PN)2 (6) and [(FcCC)(FcCCCC)PN](F2PN)2 (7), having both butadiyne and alkyne units on the same phosphorus atom of the heterocycle. All new compounds were characterized by IR, NMR [1H, 13C{1H}, 31P{1H}, and 19F{1H}] and HRMS studies. Compounds 1, 2, 4 and 5 have also been structurally characterized.

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