Phosphorus pentachloride

Phosphorus pentachloride

Names
IUPAC names Phosphorus pentachloride Phosphorus(V) chloride
Other names Pentachlorophosphorane
Identifiers
CAS Number	10026-13-8 Y
3D model (Jmol)	Interactive image
ChemSpider	23204 N
ECHA InfoCard	100.030.043
EC Number	233-060-3
PubChem	24819
RTECS number	TB6125000
UNII	0EX753TYDUTemplate:Fdite
UN number	1806
InChI InChI=1S/Cl5P/c1-6(2,3,4)5 N Key: UHZYTMXLRWXGPK-UHFFFAOYSA-N N InChI=1/Cl5P/c1-6(2,3,4)5 Key: UHZYTMXLRWXGPK-UHFFFAOYAP
SMILES ClP(Cl)(Cl)(Cl)Cl
Properties
Chemical formula	Cl5P
Molar mass	208.22 g·mol−1
Appearance	colourless crystals
Odor	pungent, unpleasant
Density	2.1 g/cm3
Melting point	160.5 °C (320.9 °F; 433.6 K)
Boiling point	166.8 °C (332.2 °F; 439.9 K) sublimation
Solubility in water	decomposition (exothermic)
Solubility	soluble in CS2, chlorocarbons, benzene
Vapor pressure	1.11 kPa (80 °C) 4.58 kPa (100 °C)
Structure
Crystal structure	tetragonal
Coordination geometry	D3h (trigonal bipyramidal)
Dipole moment	0 D
Thermochemistry
Specific heat capacity (C)	111.5 J/mol·K
Std molar entropy (So298)	364.2 J/mol·K
Hazards
Safety data sheet	ICSC 0544
GHS pictograms
GHS signal word	Danger
GHS hazard statements	H302, H314, H330, H373
GHS precautionary statements	P260, P280, P284, P305+351+338, P310
EU classification (DSD)	T+
R-phrases	R14, R22, R26, R34, R48/20
S-phrases	(S1/2), S7/8, S26, S36/37/39, S45
NFPA 704	0 3 2 W
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (median dose)	660 mg/kg (rat, oral)
LC50 (median concentration)	205 mg/m3 (rat)
LCLo (lowest published)	1020 mg/m3 (mouse, 10 min)
US health exposure limits (NIOSH):
PEL (Permissible)	TWA 1 mg/m3
REL (Recommended)	TWA 1 mg/m3
IDLH (Immediate danger)	70 mg/m3
Related compounds
Related phosphorus pentahalides	Phosphorus pentafluoride Phosphorus pentabromide Phosphorus pentaiodide
Related compounds	Phosphorus trichloride Phosphoryl chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Phosphorus pentachloride is the chemical compound with the formula PCl₅. It is one of the most important phosphorus chlorides, others being PCl₃ and POCl₃. PCl₅ finds use as a chlorinating reagent. It is a colourless, water- and moisture-sensitive solid, although commercial samples can be yellowish and contaminated with hydrogen chloride.

The structures for the phosphorus chlorides are invariably consistent with VSEPR theory. The structure of PCl₅ depends on its environment. Gaseous and molten PCl₅ is a neutral molecule with trigonal bipyramidal (D_3h) symmetry. The hypervalent nature of this species (as well as for PCl−
6, see below) can be explained with the inclusion of non-bonding MOs (Molecular orbital theory) or resonance (Valence bond theory). This trigonal bipyramidal structure persists in non-polar solvents, such as CS₂ and CCl₄. In the solid state PCl₅ is ionic, formulated PCl+
4PCl−
6.

In solutions of polar solvents, PCl₅ undergoes "autoionization". Dilute solutions dissociate according to the following equilibrium:

At higher concentrations, a second equilibrium becomes more prevalent:

The cation PCl+
4 and the anion PCl−
6 are tetrahedral and octahedral, respectively. At one time, PCl₅ in solution was thought to form a dimeric structure, P₂Cl₁₀, but this suggestion is not supported by Raman spectroscopic measurements.