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			{{good article}}
	{{chembox		{{chembox
			| Verifiedfields = changed
	| verifiedrevid = 402144842
			| Watchedfields = changed
	| Name = Hexachlorophosphazene
			| verifiedrevid = 402146390
	| ImageFile = Hexachlorotriphosphazene-2D-dimensions.png
			| ImageFile = Hexachlorotriphosphazene-2D-dimensions.png
	<!-- | ImageSize = 200px -->
	| ImageName = Hexachlorophosphazene		| ImageName = Hexachlorophosphazene conventional formula and bond lengths
	| ImageFile1 = Hexachlorophosphazene-from-xtal-2006-3D-balls-B.png		| ImageFile1 = Hexachlorophosphazene-from-xtal-2006-3D-balls-B.png
			| ImageName1 = Hexachlorophosphazene ball-and-stick model
	<!-- | ImageSize1 = 150px -->
			| IUPACName = 2,2,4,4,6,6-Hexachloro-1,3,5,2λ<sup>5</sup>,4λ<sup>5</sup>,6λ<sup>5</sup>-triazatriphosphinine
	| ImageName1 = Hexachlorophosphazene
			| OtherNames = {{ubl|Phosphonitrilic chloride trimer|Hexachlorotriphosphazene|Hexachlorocyclotriphosphazene|Triphosphonitrilic chloride|2,2,4,4,6,6-hexachloro-2,2,4,4,6,6-hexahydro-1,3,5,2,4,6-triazatriphosphorine}}
	| IUPACName = Hexachlorotriphosphazene
			|Section1={{Chembox Identifiers
	| OtherNames = Triphosphonitrilic chloride<br/>Phosphonitrilic chloride, Hexachlorocyclotriphosphazene<br/>2,2,4,4,6,6-hexachloro-2,2,4,4,6,6-<br/>hexahydro-1,3,5,2,4,6-Triazatriphosphorine
			| SMILES = N1=P(N=P(N=P1(Cl)Cl)(Cl)Cl)(Cl)Cl
	| Section1 = {{Chembox Identifiers
			| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| SMILES = N1=P(N=P(N=P1(Cl)Cl)(Cl)Cl)(Cl)Cl
	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| ChemSpiderID = 190959		| ChemSpiderID = 190959
	| PubChem = 220225		| PubChem = 220225
	| InChI = 1/Cl6N3P3/c1-10(2)7-11(3,4)9-12(5,6)8-10		| InChI = 1/Cl6N3P3/c1-10(2)7-11(3,4)9-12(5,6)8-10
	| InChIKey = UBIJTWDKTYCPMQ-UHFFFAOYAJ		| InChIKey = UBIJTWDKTYCPMQ-UHFFFAOYAJ
			| ChEMBL_Ref = {{ebicite|correct|EBI}}
			| ChEMBL = 2022081
			| EC_number = 213-376-8
	| StdInChI_Ref = {{stdinchicite|correct|chemspider}}		| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
	| StdInChI = 1S/Cl6N3P3/c1-10(2)7-11(3,4)9-12(5,6)8-10		| StdInChI = 1S/Cl6N3P3/c1-10(2)7-11(3,4)9-12(5,6)8-10
Line 22:		Line 25:
	| StdInChIKey = UBIJTWDKTYCPMQ-UHFFFAOYSA-N		| StdInChIKey = UBIJTWDKTYCPMQ-UHFFFAOYSA-N
	| CASNo = 940-71-6		| CASNo = 940-71-6
	| CASNo_Ref = {{cascite|correct|CAS}}		| CASNo_Ref = {{cascite|correct|CAS}}
			| UNII_Ref = {{fdacite|correct|FDA}}
	| EINECS =
	| RTECS =		| UNII = 7VR28MTM9D
			| EINECS =
	}}
			| RTECS =
	| Section2 = {{Chembox Properties
			}}
	| Formula = N<sub>3</sub>Cl<sub>6</sub>P<sub>3</sub>
			|Section2={{Chembox Properties
	| MolarMass = 347.66 g/mol
			| Formula = {{chem2|(NPCl2)3}}
	| Appearance = colorless crystals
			| N=3|P=3|Cl=6
	| Density = 1.98 g/mL at 25 °C
			| Appearance = colourless solid
	| Solubility = decomp.
			| Density = 1.98 g/mL at 25 °C
	| Solvent = chlorocarbons
			| Solubility = decomposes
	| SolubleOther = soluble
			| Solvent1 = carbon tetrachloride
	| MeltingPt = 112–15 °C
			| Solubility1 = {{ubl|24.5 wt % (20 °C)|35.6 wt % (40 °C)|39.2 wt % (60 °C)}}
	| BoilingPt = decomp.
			| Solvent2 = cyclohexane
	}}
			| Solubility2 = {{ubl|22.3 wt % (20 °C)|36.8 wt % (40 °C)|53.7 wt % (60 °C)}}
	| Section3 = {{Chembox Structure
			| Solvent3 = xylene
	| CrystalStruct =
			| Solubility3 = {{ubl|27.7 wt % (20 °C)|38.9 wt % (40 °C)|50.7 wt % (60 °C)}}
	| Dipole = 0 ]
			| MeltingPtC = 112 to 114
	}}
			| BoilingPt = decomposes (above 167 °C)
	| Section7 = {{Chembox Hazards
			| SublimationConditions = 60 °C at 0.05 Torr
	| ExternalMSDS =
			| RefractIndex = 1.62 (589 nm)
	| EUIndex = Not listed
			| MagSus = −149×10<sup>−6</sup> cm<sup>3</sup>/mol
	| MainHazards = mild irritant
			}}
	| FlashPt = Non-flammable
			|Section3={{Chembox Structure
	| RPhrases =
			| PointGroup = D<sub>3h</sub>
	| SPhrases =
			| LattConst_a = 13.87 Å
	}}
			| LattConst_b = 12.83 Å
	| Section8 = {{Chembox Related
			| LattConst_c = 6.09 Å
	| OtherCpds =
			| UnitCellFormulas = 4
	}}
			| MolShape = ] (slightly ruffled)
			| CrystalStruct = ]
			| SpaceGroup = 62 (Pnma, D{{sup sub|16|2h}})
			| Dipole = 0 ]
			}}
			| Section4 = {{Chembox Thermochemistry
			| HeatCapacity =
			| Entropy =
			| DeltaHform = −812.4 kJ/mol
			| DeltaGfree =
			| DeltaHcombust =
			| DeltaHfus =
			| DeltaHvap = 55.2 kJ/mol
			| DeltaHsublim = 76.2 kJ/mol
			}}
			|Section7={{Chembox Hazards
			| ExternalSDS =
			| MainHazards = mild irritant
			| FlashPt = Non-flammable
			| GHSPictograms = {{GHS05}}
			| GHSSignalWord = Danger
			| HPhrases = {{H-phrases|314}}
			| PPhrases = {{P-phrases|260|264|280|301+330+331|303+361+353|304+340|305+351+338|310|321|363|405|501}}
			}}
			|Section8={{Chembox Related
			| OtherCompounds = {{ubl|]|]|]|]|]|]|]|]}}
			}}
	}}		}}
			'''Hexachlorophosphazene''' is an ] with the ] {{chem2|(NPCl2)3|auto=1}}. The molecule has a ], ] backbone consisting of alternating ] and ] atoms, and can be viewed as a ] of the ] {{chem2|N\tPCl2}} (phosphazyl dichloride). Its classification as a ] highlights its relationship to ].<ref name=":0">{{Cite journal|last=Allen|first=Christopher W.|date=1991-03-01|title=Regio- and stereochemical control in substitution reactions of cyclophosphazenes|url=https://pubs.acs.org/doi/abs/10.1021/cr00002a002|journal=Chemical Reviews|volume=91|issue=2|pages=119–135|doi=10.1021/cr00002a002|issn=0009-2665}}</ref> There is large academic interest in the compound relating to the phosphorus-nitrogen bonding and phosphorus reactivity.<ref name="G&E" /><ref name=":1">{{Cite journal|last1=Chaplin|first1=Adrian B.|last2=Harrison|first2=John A.|last3=Dyson|first3=Paul J.|date=2005-11-01|title=Revisiting the Electronic Structure of Phosphazenes|url=https://doi.org/10.1021/ic0511266|journal=Inorganic Chemistry|volume=44|issue=23|pages=8407–8417|doi=10.1021/ic0511266|pmid=16270979|issn=0020-1669}}</ref>
	'''Hexachlorophosphazene''' is an ] with the formula (NPCl<sub>2</sub>)<sub>3</sub>. The molecule has a cyclic backbone consisting of alternating ] and ] atoms. It can be viewed as a trimer of the hypothetical compound N≡PCl<sub>2</sub>. Hexachlorophosphazene together with the related (NPCl<sub>2</sub>)<sub>4</sub> are precursors to inorganic polymers called polyphosphazenes.
			Occasionally, commercial or suggested practical applications have been reported, too, utilising hexachlorophosphazene as a precursor chemical.<ref name="G&E" /><ref name=":3">Mark, J. E.; Allcock, H. R.; West, R. “Inorganic Polymers” Prentice Hall, Englewood, NJ: 1992. {{ISBN|0-13-465881-7}}.</ref> Derivatives of noted interest include the hexalkoxyphosphazene lubricants obtained from ] of hexachlorophosphazene with ]s,<ref name=":3" /> or chemically resistant inorganic polymers with desirable thermal and mechanical properties known as ]s produced from the ] of hexachlorophosphazene.<ref name="G&E" /><ref name=":3" />
			==Structure and characterisation==
			=== Bond lengths and conformation ===
			Hexachlorophosphazene is a ], containing a {{chem2|P3N3}} core with alternating ] and ] atoms, and two additional ] atoms bonded to each phosphorus atom. Hexachlorophosphazene molecule contains six equivalent P–N bonds, for which the adjacent P–N distances are 157 ].<ref name=":0" /><ref name="G&E" /><ref name=":2">{{cite journal|last1=Bartlett|first1=Stewart W.|last2=Coles|first2=Simon J.|last3=Davies|first3=David B.|last4=Hursthouse|first4=Michael B.|last5=i̇Bişogˇlu|first5=Hanife|last6=Kiliç|first6=Adem|last7=Shaw|first7=Robert A.|last8=Ün|first8=İlker|year=2006|title=Structural investigations of phosphorus–nitrogen compounds. 7. Relationships between physical properties, electron densities, reaction mechanisms and hydrogen-bonding motifs of N3P3Cl(6 − n)(NHBu t ) n derivatives|journal=Acta Crystallographica Section B: Structural Science|volume=62|issue=2|pages=321–329|doi=10.1107/S0108768106000851|pmid=16552166|doi-access=free}}</ref> This is characteristically shorter than the ''ca''. 177 pm P–N bonds in the valence saturated ] analogues.<ref name=":1" />
			The molecule possesses D<sub>3h</sub> symmetry, and each phosphorus center is ] with a Cl–P–Cl angle of 101°.<ref name=":2" />
			The {{chem2|P3N3}} ring in hexachlorophosphazene deviates from planarity and is slightly ruffled (see ]).<ref name="G&E" /> By contrast, the {{chem2|P3N3}} ring in the related ] species is completely planar.<ref name="G&E" />
			=== Characterisation methods ===
			] spectroscopy is the usual method for assaying hexachlorophosphazene and its reactions.<ref name=":4" /><ref name=":5" /><ref name=":6">{{Cite journal|last1=Dhiman|first1=Nisha|last2=Mohanty|first2=Paritosh|date=2019-10-28|title=A nitrogen and phosphorus enriched pyridine bridged inorganic–organic hybrid material for supercapacitor application|url=https://pubs.rsc.org/en/content/articlelanding/2019/nj/c9nj03976g|journal=New Journal of Chemistry|language=en|volume=43|issue=42|pages=16670–16675|doi=10.1039/C9NJ03976G|s2cid=208761169|issn=1369-9261}}</ref> Hexachlorophosphazene exhibits a single resonance at 20.6 ppm as all P environments are chemically equivalent.<ref name=":5" /><ref name=":6" />
			In it ], the 1370 and 1218&nbsp;cm<sup>−1</sup> vibrational bands are assigned to ν<sub>P–N</sub> stretches.<ref name=":5" /><ref name=":6" /> Other bands are found at 860 and 500–600&nbsp;cm<sup>−1</sup>, respectively assigned to ring and ν<sub>P–Cl</sub>.<ref name=":6" />
			Hexachlorophosphazene and many of its derivatives have been characterized by single crystal ].<ref name="G&E" /><ref name=":2" />
			==Bonding==
			[[File:Cyclotriphosphazene_bonding.png|centre|515x515px|Depictions of P–N bonding in a general cyclotriphosphazene: left, a representation of alternating single and double P–N bonds (does not account for equal bond lengths), used as a matter of convention;<ref name=":0" /> middle, the earlier proposed delocalised ring system (discredited due to infeasibility of P 3''d'' participation<ref name=":1" />); right, the most accurate description to current knowledge, where the majority of the bonding is ionic<ref name=":0" /><ref name=":1" />
			|thumb]]
			===Early analyses===
			Cyclophosphazenes such as hexachlorophosphazene are distinguished by notable stability and equal P–N bond lengths which, in many such cyclic molecules, would imply delocalization or even aromaticity. To account for these features, early bonding models starting from the mid-1950s invoked a delocalised π system arising from the overlap of N 2''p'' and P 3''d'' ]s.<ref name=G&E/><ref name=":1" />
			===Modern bonding models===
			Starting from the late 1980s, more modern calculations and the lack of spectroscopic evidence reveal that the P 3''d'' contribution is negligible, invalidating the earlier hypothesis.<ref name=":1" /> Instead, a charge separated model is generally accepted.<ref name=":0" /><ref name=":1" />
			According to this description, the P–N bond is viewed as a very polarised one (between notional {{chem2|P+}} and {{chem2|N–}}), with sufficient ionic character to account for most of the bond strength.<ref name=":0" /><ref name=":1" />
			The rest (~15%) of the bond strength may be attributed to a ] interaction: the N lone pairs can ] into π-accepting σ* molecular orbitals on the P.<ref name=":1" />
	==Synthesis==		==Synthesis==
			The synthesis of hexachlorophosphazene was first reported by ] in 1834. In that report he describes experiments conducted with ].<ref>{{cite journal |author=J. Liebig |title=Nachtrag der Redaction |journal=Ann. Pharm. |volume=11 |pages=139–150 |year=1834 |doi=10.1002/jlac.18340110202|url=https://zenodo.org/record/1426908}}</ref> They found that ] ({{chem2|PCl5}}) and ] ({{chem2|NH3}}) react ] to yield a new substance that could be washed with cold water to remove the ] ({{chem2|Cl}}) coproduct. The new compound contained ], ], and ], on the basis of ]. It was sensitive toward ] by hot water.<ref name=G&E>{{Greenwood&Earnshaw2nd}}</ref>
	The reaction of ] and ] affords substances with the ] PNCl<sub>2</sub>:<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.</ref> Purification by sublimation gives mainly the ] (PNCl<sub>2</sub>)<sub>3</sub> and ] (PNCl<sub>2</sub>)<sub>4</sub>. These rings were described by ] in 1832<ref name="stokes1895"/><ref name="liebig">Liebig-Wöhler, Briefwechsel vol. 1, 63; Ann. Chem. (Liebig), vol. 11 (1834), 146.</ref> in his study of the reaction of PCl<sub>5</sub> and ]:
			Modern syntheses are based on the developments by Schenk and Römer who used ammonium chloride in place of ammonia and ] ] ]. By replacing ammonia with ammonium chloride allows the reaction to proceed without a strong ] associated with the {{chem2|NH3}}/{{chem2|PCl5}}. Typical ] solvents are ] or ], which tolerate the ] (HCl) side product. Since ammonium chloride is insoluble in chlorinated solvents, workup is facilitated.<ref>{{cite book|author=R. Klement|chapter=Phosphonitrilic Chlorides|title=Handbook of Preparative Inorganic Chemistry, 2nd Ed. |editor=G. Brauer|publisher=Academic Press|year=1963|place=NY, NY|volume=1|pages=575}}</ref><ref>{{cite book |doi=10.1002/9780470132371.ch28|chapter=Trimeric Phosphonitrile Chloride and Tetrameric Phosphonitrile Chloride|series=Inorganic Syntheses|year=2007|last1=Nielsen|first1=Morris L.|last2=Cranford|first2=Garland|title=Inorganic Syntheses|pages=94–97|volume=6|isbn=9780470132371|orig-year=1960}}</ref> For the reaction under such conditions, the following ] applies:
	: PCl<sub>5</sub> + NH<sub>4</sub>Cl → 1/''n'' (NPCl<sub>2</sub>)<sub>''n''</sub> + 4 HCl
			:{{chem2|''n'' Cl + ''n'' PCl5 → (NPCl2)_{''n''} + ''n'' HCl}}
	Typically reactions are conducted in ] solution.
			where ''n'' can usually take values of 2 (the dimer ]), 3 (the trimer hexachlorotriphosphazene), and 4 (the tetramer ]).<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. {{ISBN|0-12-352651-5}}.</ref>
			]
	==Inorganic rings==
	Chemists have long known of rings containing carbon, e.g. ], ], and ]. Related cyclic compounds lacking in carbon have also been studied. Hexachlorophosphazene is one such inorganic ring. Other well known inorganic rings include ], ], and the cyclic ]s.
			Purification by sublimation gives mainly the ] and ]. Slow ] at approximately 60&nbsp;°C affords the pure trimer free of the tetramer.<ref name=":4" /> Reaction conditions such as temperature may also be tuned to maximise the yield of the trimer at the expense of the other possible products; nonetheless, commercial samples of hexachlorophosphazene usually contain appreciable amounts of octachlorotetraphosphazene, even up to 40%.<ref name=":4">{{Cite book|last=Allcock, H. R.|url=https://www.worldcat.org/oclc/838102247|title=Phosphorus-nitrogen compounds ; cyclic, linear, and high polymeric systems|date=1972|publisher=Academic Press|isbn=978-0-323-14751-4|location=New York|oclc=838102247}}</ref>
	=="Inorganic rubber"==
	Hexachlorophosphazene is a precursor to ] or "inorganic rubber", whose discovery is attributed to ] in 1896.<ref name="stokes1895">H. N. Stokes (1895), . American Chemical Journal, vol. 17, p. 275.</ref><ref name="stokes1896">H. N. Stokes (1896), American Chemical Journal, vol. 18 issue 8, p. 629.</ref><ref>Mark, J. E.; Allcock, H. R.; West, R. “Inorganic Polymers” Prentice Hall, Englewood, NJ: 1992. ISBN 0-13-465881-7.</ref> Upon heating to ca. 250 °C, the trimer undergoes ] to give the linear polymer (PNCl<sub>2</sub>)<sub>''n''</sub>. Subsequent replacement of the chloride centers by other groups, especially ]s, yields many ]s, some with commercial uses.
			=== Formation mechanism ===
	==See also==
			The mechanism of the above reaction has not been resolved, but it has been suggested that ] is found in its ionic form {{chem2|+−}} (tetrachlorophosphonium hexachlorophosphate(V)) and the reaction proceeds ''via'' ] of {{chem2|+}} (tetrachlorophosphonium) by ] (from Cl}}]] ]).<ref name="G&E" /> ] of ] (the major ]) creates a reactive ] ]
	* ] (PNCl<sub>2</sub>)<sub>4</sub><ref name="stokes1895"/>
			:{{chem2|NH3 + + → HN\dPCl3 + HCl + ]}}
			which through further attack of {{chem2|+}} and subsequent HCl elimination, creates a growing ] intermediate
			:{{chem2|HN\dPCl3 + + → + + HCl}}
			:{{chem2|NH3 + + → HN\dPCl2\sN\dPCl3 + HCl + H+}}, ''etc.''
			until an eventual ] leads to the formation of one of the ] ]s.<ref name="G&E" />
			==Reactions==
			=== Substitution at P ===
			Hexachlorophosphazene reacts readily with ] ]s and ].<ref name=":0" /><ref name=G&E/>
			]
			The ] poly] of ] by alkoxide proceeds via displacement of chloride at separate phosphorus centers:<ref name=":0" />
			:{{chem2|(NPCl2)3 + 3 NaOR → (NPCl(OR))3 + 3 ]}}
			:{{chem2|(NPCl(OR))3 + 3 NaOR → (NP(OR)2)3 + 3 NaCl}}
			The observed ] is due to the combined steric effects and oxygen lone pair π-backdonation (which deactivates already substituted P atoms).<ref name=":0" /><ref name="G&E" />
			=== Ring-opening polymerisation ===
			Heating hexachlorophosphazene to ''ca''. 250&nbsp;°C induces polymerisation.<ref name=":0" /><ref name="G&E" /><ref name=":3" /><ref name=":4" /> The tetramer also polymerises in this manner, although more slowly.<ref name=":3" /> The conversion is a type of ] (ROP).<ref name=":4" /><ref name=":5">{{cite journal|last1=Heston|first1=Amy J.|last2=Panzner|first2=Matthew J.|last3=Youngs|first3=Wiley J.|last4=Tessier|first4=Claire A.|year=2005|title=Lewis Acid Adducts of &#91;PCl2N&#93;3|journal=Inorganic Chemistry|volume=44|issue=19|pages=6518–6520|doi=10.1021/ic050974y|pmid=16156607}}</ref> The ROP mechanism is found to be catalysed by ], but is overall not very well understood.<ref name=":5" /> Prolonged heating of the polymer at higher temperatures (''ca''. 350&nbsp;°C) will cause ].<ref name="G&E" />
			The structure of the inorganic ] product (]) comprises a linear –{{chem2|(N\dP(\sCl)2\s)_{''n''}|}} chain, where ''n'' ~ 15000.<ref name="G&E" /><ref name=":3" /> It was first observed in the late 19th century and its form after chain ]ing has been called "inorganic rubber" due to its ]ic behaviour.<ref name=":3" />]
			This polydichlorophosphazene product is the starting material for a wide class of polymeric compounds, collectively known as ]s. Substitution of the chloride groups by other nucleophilic groups, especially ]s as laid out above, yields numerous characterised derivatives.<ref name="G&E" /><ref name=":3" /><ref name=":4" />
			===Lewis basicity===
			The nitrogen centres of hexachlorophosphazene are weakly basic, and this Lewis base behaviour has been suggested to play a role in the polymerisation mechanism.<ref name=":5" /> Specifically, hexachlorophosphazene has been reported to form adducts of various stoichiometries with Lewis acids ], ], ], ], ], ], but no isolable product with ].<ref name=":5" />
			Among these, the best structurally characterised are the 1:1 adducts with aluminium trichloride or with gallium trichloride; they are found with the Al/Ga atom bound to a N and assume a more prominently distorted chair conformation compared to the free hexachlorophosphazene.<ref name=":5" /> The adducts also exhibit ] behaviour in solution for temperatures down to −60&nbsp;°C, which can be monitored with ] and ].<ref name=":5" />
			=== Coupling reagent ===
			Hexachlorophosphazene has also found applications in research by enabling aromatic ] reactions between ] and either ''N'',''N''-dialkylanilines or ], resulting in 4,4'-substituted ] derivatives, postulated to go through a cyclophosphazene pyridinium salt intermediate.<ref name=":4" />
			The compound may also be used as a ] reagent for the synthesis of ]s in chloroform, though for this application the tetramer octachlorotetraphosphazene usually proves more effective.<ref name=":4" />
			=== Photochemical degradation ===
			Both the trimer and tetramer in hydrocarbon solutions ] react forming clear liquids identified as alkyl-substituted derivatives {{chem2|(NPCl_{2−''x''}R_{''x''})_{''n''}|}}, where ''n'' = 3, 4.<ref name=":4" /> Such reactions proceed under prolonged ] (]) illumination without affecting the {{chem2|P_{''n''}N_{''n''}|}} rings. Solid films of the trimer and tetramer will not undergo any chemical change under such irradiation conditions.<ref name=":4" />
			== Applications ==
			The hexalkoxyphosphazenes (especially the ] species), resulting from the nucleophilic hexasubstitution of the hexachlorophosphazene P atoms, have attracted interest for their high thermal and chemical stability as well as their low ].<ref name=":3" /> Certain hexalkoxyphosphazenes (such as the hexa-phenoxy derivative) have been put to commercial use as fireproof materials and high temperature lubricants.<ref name=":3" />
			Polyphosphazenes obtained from polymerised hexachlorophosphazene (]) have garnered attention within the field of ]s. The ]ic and ] properties have been investigated.<ref name="G&E" /><ref name=":3" /> Some of them appear promising for future applications as fibre- or membrane-forming high performance materials, since they combine transparency, ] flexibility, tunable ] or ], and various other ].<ref name=":3" />
			Polyphosphazene-based components have been used in ]s, ]s and ]s, where the polyphosphazenes confer fire resistance, imperviousness to oils, and flexibility even at very low temperatures.<ref name="G&E" />
			==Further reading==
			*Discovery of cyclophosphazenes: Liebig-Wöhler, Briefwechsel vol. 1, 63; Ann. Chem. (Liebig), vol. 11 (1834), 146.
			*First reports on their polymerisation: H. N. Stokes (1895), . American Chemical Journal, vol. 17, p.&nbsp;275.H. N. Stokes (1896), American Chemical Journal, vol. 18 issue 8, p.&nbsp;629.
			*Example of hexalkoxyphosphazene synthesis from hexachlorophosphazene and structure description: {{Cite journal|last1=Allcock|first1=Harry R.|last2=Ngo|first2=Dennis C.|last3=Parvez|first3=Masood|last4=Whittle|first4=Robert R.|last5=Birdsall|first5=William J.|date=1991-03-01|title=Syntheses and structures of cyclic and short-chain linear phosphazenes bearing 4-phenylphenoxy side groups|url=https://doi.org/10.1021/ja00007a041|journal=Journal of the American Chemical Society|volume=113|issue=7|pages=2628–2634|doi=10.1021/ja00007a041|issn=0002-7863}}
			*Novel hexalkoxyphosphazene synthesis not starting from hexachlorophosphazene: {{Cite journal|last1=Ye|first1=Chengfeng|last2=Zhang|first2=Zefu|last3=Liu|first3=Weimin|date=2002-01-01|title=A Novel Synthesis of Hexasubstituted Cyclotriphosphazenes|url=https://doi.org/10.1081/SCC-120002003|journal=Synthetic Communications|volume=32|issue=2|pages=203–209|doi=10.1081/SCC-120002003|s2cid=97319633|issn=0039-7911}}
	==References==		==References==
	{{reflist}}		{{reflist}}
			{{commons category|Hexachlorophosphazene|lcfirst=yes}}
	{{commonscat|hexachlorophosphazene}}
	]		]
	]		]
	]		]
	]		]
	]		]
			]
			]
	]
			]