Lead(IV) chloride

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Lead(IV) chloride
t

Lead tetrachloride contaminated with lead(II) chloride
Names
IUPAC name
Lead(IV) chloride
Systematic IUPAC name
Tetrachloroplumbane
Identifiers
3D model (
JSmol
)
ChemSpider
  • InChI=1S/4ClH.Pb/h4*1H;/q;;;;+4/p-4
    Key: PJYXVICYYHGLSW-UHFFFAOYSA-J
  • Cl[Pb](Cl)(Cl)Cl
Properties
PbCl4
Molar mass 349.012 g/mol[1]
Appearance yellow oily liquid[2]
Density 3.2 g⋅cm−3[1]
Melting point −15 °C (5 °F; 258 K)[1] stable below 0 °C (32 °F; 273 K)[2]
Boiling point 50 °C (122 °F; 323 K)[1] decomposes
Reacts
Solubility hydrochloric acid
Structure
4
tetrahedral[3]
Thermochemistry
Std enthalpy of
formation
fH298)
-328.9 kJ/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Lead tetrachloride, also known as lead(IV) chloride, has the molecular formula PbCl4. It is a yellow, oily liquid which is stable below 0 °C, and decomposes at 50 °C.[2] It has a tetrahedral configuration, with lead as the central atom. The Pb–Cl covalent bonds have been measured to be 247 pm and the bond energy is 243 kJ⋅mol−1.[4]

Synthesis

Lead tetrachloride can be made by reacting lead(II) chloride PbCl2, and hydrochloric acid HCl, in the presence of chlorine gas (Cl2),[5] leading to the formation of chloroplumbic acid H2PbCl6. It is then converted to the ammonium salt (NH4)2PbCl6 by adding ammonium chloride (NH4Cl). Finally, the solution is treated with concentrated sulfuric acid H2SO4, to separate out lead tetrachloride. This series of reactions is conducted at 0 °C. The following equations illustrate the reaction:

PbCl2 + 2HCl + Cl2 → H2PbCl6
H2PbCl6 + 2 NH4Cl → (NH4)2PbCl6 + 2HCl
(NH4)2PbCl6 + H2SO4 → PbCl4+ 2HCl + (NH4)2SO4

Reaction with water

Unlike

cluttering and water can easily access it.[3] Also, because of the presence of empty d orbitals on the Pb atom, oxygen can bind to it before a Pb–Cl bond has to break, thus requiring less energy
. The overall reaction is thus as follow:

PbCl4 + 2H2O → PbO2(s) + 4HCl(g)

Stability

Lead tetrachloride tends to

lead dichloride and chlorine gas:[3]

PbCl4 → PbCl2 + Cl2(g)

There are reports that this reaction can proceed explosively and that the compound is best stored under pure sulfuric acid at -80 °C in the dark.[6]

The stability of the +4

inert pair effect causes lead to favor its +2 oxidation state: Pb atom loses all its outermost p electrons and ends up with a stable, filled s subshell.[7]

Toxicity

Lead is a

References

  1. ^ a b c d "Lead compounds: Lead Tetrachloride". WebElements.com. Retrieved 10 October 2012.
  2. ^ .
  3. ^ a b c d "The Chlorides of Carbon, Silicon and Lead". chemguide.co.uk. Retrieved 10 October 2012.
  4. ^ .
  5. .
  6. .
  7. ^ National Toxicology Program, Department of Health and Human Services (2011). Report on Carcinogens, Twelfth Edition (2011) - Lead and Lead Compounds (PDF). p. 251.
  8. ^ "Environmental Health & Safety - 1: General Information About Chemical Safety". Princeton UNiversity. Archived from the original on 27 April 2013. Retrieved 11 October 2012.