Antimony pentachloride

Antimony pentachloride is a chemical compound with the formula SbCl₅. It is a colourless oil, but typical samples are yellowish due to dissolved chlorine. Owing to its tendency to hydrolyse to hydrochloric acid, SbCl₅ is a highly corrosive substance and must be stored in glass or PTFE containers.

Antimony pentachloride

Antimony pentachloride
Names
IUPAC names Antimony pentachloride Antimony(V) chloride
Other names Antimonic chloride Antimony perchloride
Identifiers
CAS Number	7647-18-9 Y
3D model (JSmol)	Interactive image Interactive image
ChemSpider	10613049 Y
ECHA InfoCard	100.028.729
EC Number	231-601-8
PubChem CID	24294
RTECS number	CC5075000
UNII	0S9308207L Y
CompTox Dashboard (EPA)	DTXSID30893043
InChI InChI=1S/5ClH.Sb/h5*1H;/q;;;;;+3/p-5 Y Key: PZVOXSCNPLCIRA-UHFFFAOYSA-I Y InChI=1/5ClH.Sb.3H/h5*1H;;;;/q;;;;;+3;;;/p-5/r5ClH.H3Sb/h5*1H;1H3/q;;;;;+3/p-5 Key: KUGFODPTKMDJNG-MEZDTJOHAL InChI=1/5ClH.Sb/h5*1H;/q;;;;;+3/p-5 Key: PZVOXSCNPLCIRA-AACRGIKGAS
SMILES [Cl-].[Cl-].[Cl-].[Cl-].[Cl-].[SbH3+3] [SbH3+3].[Cl-].[Cl-].[Cl-].[Cl-].[Cl-]
Properties
Chemical formula	Cl5Sb
Molar mass	299.01 g·mol−1
Appearance	colorless or reddish-yellow (fuming) liquid, oily
Odor	pungent, offensive
Density	2.336 g/cm3 (20 °C)[1] 2.36 g/cm3 (25 °C)[2]
Melting point	2.8 °C (37.0 °F; 275.9 K)
Boiling point	140 °C (284 °F; 413 K) decomposes from 106 °C[3] 79 °C (174 °F; 352 K) at 22 mmHg[1] 92 °C (198 °F; 365 K) at 30 mmHg[2]
Solubility in water	reacts
Solubility	soluble in alcohol, HCl, tartaric acid, CHCl3, CS2, CCl4
Solubility in selenium(IV) oxychloride	62.97 g/100 g (25 °C)
Vapor pressure	0.16 kPa (25 °C) 4 kPa (40 °C) 7.7 kPa (100 °C)[4]
Magnetic susceptibility (χ)	−120.0·10−6 cm3/mol
Refractive index (nD)	1.59255
Viscosity	2.034 cP (29.4 °C)[1] 1.91 cP (35 °C)
Structure
Molecular shape	Trigonal bipyramidal
Dipole moment	0 D
Thermochemistry[3]
Heat capacity (C)	120.9 J/mol·K (gas)
Std molar entropy (S⦵298)	295 J/mol·K
Std enthalpy of formation (ΔfH⦵298)	−437.2 kJ/mol
Gibbs free energy (ΔfG⦵)	−345.35 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Inhalation hazards	Toxic
GHS labelling:[2]
Pictograms
Signal word	Danger
Hazard statements	H314, H411
Precautionary statements	P273, P280, P305+P351+P338, P310
NFPA 704 (fire diamond)	4 0 2 W OX
Flash point	77 °C (171 °F; 350 K)
Lethal dose or concentration (LD, LC):
LD50 (median dose)	1115 mg/kg, (rat, oral)[3]
NIOSH (US health exposure limits):
PEL (Permissible)	TWA 0.5 mg/m3 (as Sb)[5]
REL (Recommended)	TWA 0.5 mg/m3 (as Sb)[5]
Related compounds
Other anions	Antimony pentafluoride
Other cations	Phosphorus pentachloride
Related compounds	Antimony trichloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Preparation and structure

Antimony pentachloride is prepared by passing chlorine gas into molten antimony trichloride:

SbCl₃ + Cl₂ → SbCl₅

Gaseous SbCl₅ has a trigonal bipyramidal structure.^[6]

Reactions

This compounds reacts with water to form antimony pentoxide and hydrochloric acid:^[7]

2 SbCl₅ + 5 H₂O → Sb₂O₅ + 10 HCl

The mono- and tetrahydrates are known, SbCl₅·H₂O and SbCl₅·4H₂O.

This compound forms adducts with many Lewis bases. SbCl₅ is a soft Lewis acid and its ECW model parameters are E_A = 3.64 and C_A = 10.42. It is used as the standard Lewis acid in the Gutmann scale of Lewis basicity.^[8][9]

It is also a strong oxidizing agent.^[10] For example aromatic ethers are oxidized to their radical cations according to the following stoichiometry:^[11]

3 SbCl₅ + 2 ArH → 2 (ArH+)(SbCl₆⁻) + SbCl₃

Applications

Antimony pentachloride is used as a polymerization catalyst and for the chlorination of organic compounds.

Precautions

Antimony pentachloride is a highly corrosive substance that should be stored away from heat and moisture. It is a chlorinating agent and, in the presence of moisture, it releases hydrogen chloride gas. Because of this, it may etch even stainless-steel tools (such as needles), if handled in a moist atmosphere. It should not be handled with non-fluorinated plastics (such as plastic syringes, plastic septa, or needles with plastic fittings), since it melts and carbonizes plastic materials.^[12]