Octachlorotetraphosphazene

Octachlorotetraphosphazene is an inorganic compound with the formula (NPCl₂)₄. The molecule has a cyclic, unsaturated backbone consisting of alternating phosphorus and nitrogen centers, and can be viewed as a tetramer of the hypothetical compound N≡PCl₂.

Octachlorotetraphosphazene

Octachlorotetraphosphazene structure (ball-and-stick)
Names
IUPAC name 2,2,4,4,6,6,8,8-Octachloro-1,3,5,7,2λ5,4λ5,6λ5,8λ5-tetrazatetraphosphocine
Other names Phosphonitrilic chloride tetramer Octachlorocyclotetraphosphazene Tetraphosphonitrilic chloride 2,2,4,4,6,6,8,8-octachloro-2,2,4,4,6,6,8,8-octahydro-1,3,5,7,2,4,6,8-tetraazatetraphosphocine 2,2,4,4,6,6,8,8-octachloro-1,3,5,7-tetraza-2λ5,4λ5,6λ5,8λ5-tetraphosphacycloocta-1,3,5,7-tetraene
Identifiers
CAS Number	2950-45-0
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL3344300
ChemSpider	68764
EC Number	220-972-1
PubChem CID	76285
CompTox Dashboard (EPA)	DTXSID7062740
InChI InChI=1S/Cl8N4P4/c1-13(2)9-14(3,4)11-16(7,8)12-15(5,6)10-13 Key: PEJQKHLWXHKKGS-UHFFFAOYSA-N
SMILES N1=P(N=P(N=P(N=P1(Cl)Cl)(Cl)Cl)(Cl)Cl)(Cl)Cl
Properties
Chemical formula	N4Cl8P4
Molar mass	463.55 g/mol
Appearance	Colorless solid
Density	2.27 g/mL at -173 °C
Melting point	123 to 124 °C (253 to 255 °F; 396 to 397 K)
Boiling point	188 °C at 15 Torr
Solubility in water	Decomposes
Solubility in hexane	7.0 g/100g (20 °C)
Solubility in toluene	1.8 g/100g (20 °C)
Solubility in CCl4	1.6 g/100g (20 °C)
Refractive index (nD)	1.675 (589 nm)
Structure
Crystal structure	Tetragonal
Space group	86
Point group	D4h
Dipole moment	0.39 D
Thermochemistry
Std enthalpy of formation (ΔfH⦵298)	-1084.9 kJ·mol−1
Enthalpy of vaporization (ΔfHvap)	64.9 kJ·mol−1 (325 °C)
Enthalpy of sublimation (ΔfHsublim)	95.9–97.5 kJ·mol−1
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Mild irritant
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H314
Precautionary statements	P260, P280, P304+P340, P305+P351+P338, P363
Flash point	Non-flammable
Related compounds
Related compounds	Hexachlorophosphazene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

The compound has not been studied as much as the related species hexachlorotriphosphazene, in the samples of which octachlorotetraphosphazene is usually found as an unwanted contamintant.^[1]

Structure and bonding

Octachlorotetraphosphazene has a P₄N₄ core with six equivalent P–N bonds.^[2]

Synthesis

NH₄Cl + PCl₅ → 1/n (NPCl₂)_n + HCl

Reactions

Substitution at P

Some spiro-, ansa-, and spiro-ansa-cyclic derivatives have been prepared via nucleophilic substitution of octachlorotetraphosphazene with alkoxides.^[3]