Structure and Conformation of the Medium-Sized Chlorophosphazene Rings

Abstract

Medium-sized cyclic oligomeric phosphazenes [PCl2N]m (where m = 5-9) that were prepared from the reaction of PCl5 and NH4Cl in refluxing chlorobenzene have been isolated by a combination of sublimation/extraction and column chromatography from the predominant products [PCl2N]3 and [PCl2N]4. The medium-sized rings [PCl2N]m have been characterized by electrospray ionization-mass spectroscopy (ESI-MS), their (31)P chemical shifts have been reassigned, and their T1 relaxation times have been obtained. Crystallographic data has been recollected for [PCl2N]5, and the crystal structures of [PCl2N]6, and [PCl2N]8 are reported. Halogen-bonding interactions were observed in all the crystal structures of cyclic [PCl2N]m (m = 3-5, 6, 8). The crystal structures of [P(OPh)2N]7 and [P(OPh)2N]8, which are derivatives of the respective [PCl2N]m, are also reported. Comparisons of the intermolecular forces and torsion angles of [PCl2N]8 and [P(OPh)2N]8 with those of three other octameric rings are described. The comparisons show that chlorophosphazenes should not be considered prototypical, in terms of solid-state structure, because of the strong influence of halogen bonding.

2-Naphthylthio Cyclotriphosphazene Derivatives: Synthesis, Characterization, Crystallographic and Fluorescence Properties

“…Interestingly, it was observed that the naphthylthio groups in these two isomers crystallized at very different positions (Figure 5). In the 1-naphthylthio group substituted cyclotriphosphazene compound, the distance between S-S was 3.150 Å, while this value was 3.377 Å in the 2-naphthylthio substituted cyclotriphosphazene (3). Also, the S-P-S angle of compound 3 (110.33º) is also greater than the S-P-S (98.45º) in the 1-naphthylthio isomer (Figure 5).…”

“…are the most important members of inorganic heterocyclic compounds (1)(2)(3)(4)(5)(6)(7)(8)(9). The most well-known and studied derivatives of cyclophosphazenes are trimer (hexachlorocyclotriphosphazene) and tetramer (octachlorocyclotetraphosphazene).…”

“…Molecular structure of compound 3 was confirmed by X-Ray (single crystal) diffraction technique. And therewithal, fluorescence properties of all these new compounds (3)(4)(5) were investigated first time.…”

Novel Approach for the Synthesis of Chlorophosphazene Cycles with a Defined Size via Controlled Cyclization of Linear Oligodichlorophosphazenes [Cl(PCl2=N)n–PCl3]+[PCl]6–

“…In 2014 Bowers et al [38] separated the products of the ammonolysis reaction by liquid chromatography, which made it possible to isolate the cycles (NPCl2)n = 5-9 and identify them separately from each other using 31 P NMR spectroscopy and mass spectrometry. The obtained values of chemical shifts on 31 P nuclei are given in Table 1, which contradicted the generally accepted data, in particular, the fact that the hexamer signal turns out to be shifted to the region of a weaker field relative to the pentamer singlet.…”

Novel Approach for the Synthesis of Chlorophosphazene Cycles with a Defined Size via Controlled Cyclization of Linear Oligodichlorophosphazenes [Cl(PCl2=N)n–PCl3]+[PCl6]−

“…In 2014, Bowers et al [ 39 ] separated the products of the ammonolysis reaction by liquid chromatography, which made it possible to isolate the cycles (NPCl 2 ) n = 5–9 and identify them separately from each other using 31 P NMR spectroscopy and mass spectrometry. The obtained values of chemical shifts on 31 P nuclei, given in Table 1 , contradicted the generally accepted data, in particular, the fact that the hexamer signal turns out to be shifted to the region of a weaker field relative to the pentamer singlet.…”