New results in the ammonolysis of hexafluoro-cyclo-triphosphazene: Crystal structure of P3N3F5–NH–P3N3F4NH2

The reaction of hexafluoro-cyclo-triphosphazene P3N3F6 with ammonia in acetonitrile has been studied. New compounds, (2-imino-2,4,4,6,6-pentafluoro-2λ5,4λ5,6λ5-cyclo-triphosphaza-1,3,5-trienyl)-2-amino-4,4,6,6-tetrafluoro-2λ5,4λ5,6λ5-cyclo-triphosphaza-1,3,5-triene, P3N3F5–NH–P3N3F4NH2 (2) and cis and trans isomers of non-gem-2,4-diamino-2,4,6,6-tetrafluoro-2λ5,4λ5,6λ5-cyclo-triphosphaza-1,3,5-triene, P3N3F4(NH2)2 (4, 5), were detected by GC/MS, and 31P NMR spectroscopy in reaction mixtures. X-ray diffraction analysis of P3N3F5–NH–P3N3F4NH2 (2) revealed two conformational polymorphs, 2A and 2B, the latter being built up of two different conformers that were further denoted as 2Ba (the same as the single conformer in 2A) and 2Bb. The compound 2 was characterized by spectroscopic methods and its 2D potential energy surface (PES) was described by density functional theory computations depending on two dihedral angles. The calculated PES spans over 30 kJ/mol in energy including 8 local minima and all first and second order saddle points. The occurrence of the two experimentally observed conformers 2Ba and 2Bb seems to be governed by crystal packing effects.

Graphical abstractThe reaction of hexafluoro-cyclo-triphosphazene P3N3F6 with ammonia in acetonitrile has been studied and new compounds, (2-imino-2,4,4,6,6-pentafluoro-2λ5,4λ5,6λ5-cyclo-triphosphaza-1,3,5-trienyl)-2-amino-4,4,6,6-tetrafluoro-2λ5,4λ5,6λ5-cyclo-triphosphaza-1,3,5-triene, P3N3F5–NH–P3N3F4NH2 (2), cis and trans isomers of non-gem-2,4-diamino-2,4,6,6-tetrafluoro-2λ5,4λ5,6λ5-cyclo-triphosphaza-1,3,5-triene, P3N3F4(NH2)2 (4, 5), were identified in the reaction mixture. Two conformers of the compound 2, denoted as 2A and 2B, were isolated (conformational polymorphism).Figure optionsDownload full-size imageDownload as PowerPoint slide