Lead(II) chloride

In solid PbCl₂, each lead ion is coordinated by nine chloride ions in a tricapped triangular prism formation — six lie at the vertices of a triangular prism and three lie beyond the centers of each rectangular prism face. The 9 chloride ions are not equidistant from the central lead atom, 7 lie at 280–309 pm and 2 at 370 pm.Wells A. F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications {{ISBN|0-19-855370-6}} PbCl₂ forms white orthorhombic needles.

{{gallery

|File:Cotunnite-3D-balls.png|Ball-and-stick model of part of the crystal structure of cotunnite

|File:Cotunnite-3D-ionic.png|Space-filling model

|File:Cotunnite-Pb-coordination-geometry-3D-balls.png|Coordination geometry of Pb²⁺

|File:Cotunnite-Cl-coordination-geometry-3D-balls.png|Coordination geometry of Cl⁻

|File:Cotunnite-Pb-coordination-CM-3D-balls.png|Coordination polyhedron of Pb²⁺

}}

In the gas phase, PbCl₂ molecules have a bent structure with the Cl–Pb–Cl angle being 98° and each Pb–-Cl bond distance being 2.44 Å.{{cite journal|last1 = Hargittai|first1 = I|last2 = Tremmel|first2 = J|last3 = Vajda|first3 = E|last4 = Ishchenko|first4 = A|last5 = Ivanov|first5 = A|last6 = Ivashkevich|first6 = L|last7 = Spiridonov|first7 = V|title = Two independent gas electron diffraction investigations of the structure of plumbous chloride|journal = Journal of Molecular Structure|volume = 42|pages = 147–151|year = 1977|doi = 10.1016/0022-2860(77)87038-5|bibcode = 1977JMoSt..42..147H}} Such PbCl₂ is emitted from internal combustion engines that use ethylene chloride-tetraethyllead additives for antiknock purposes.

PbCl₂ is sparingly soluble in water, solubility product K_sp = {{val|1.7e-5}} at 20 °C. It is one of only 5 commonly water-insoluble chlorides, the other 4 being thallium(I) chloride, silver chloride (AgCl) with K_sp = {{val|1.8e-10}}, copper(I) chloride (CuCl) with K_sp = {{val|1.72e-7}} and mercury(I) chloride (Hg₂Cl₂) with K_sp = {{val|1.3e-18}}.CRC Handbook of Chemistry and Physics, 79th Edition, David R. Lide (Ed), p. 8-108Brown, Lemay, Burnsten. Chemistry The Central Science. "Solubility-Product Constants for Compounds at 25 °C". (ed 6, 1994). p. 1017

Solid lead(II) chloride precipitates upon addition of aqueous chloride sources (HCl, NaCl, KCl) to aqueous solutions of lead(II) compounds, such as lead(II) nitrate and lead(II) acetate:

:{{chem2|Pb(NO3)2 + 2 HCl → PbCl2(s) + 2 HNO3}}

It also forms by treatment of basic lead(II) compounds such as Lead(II) oxide and lead(II) carbonate.

Lead dioxide is reduced by chloride as follows:

:{{chem2|PbO2 + 4 HCl → PbCl2(s) + Cl2 + 2 H2O}}

It also formed by the oxidation of lead metal by copper(II) chloride:

:{{chem2|Pb + CuCl2 → PbCl2 + Cu}}

Or most straightforwardly by the action of chlorine gas on lead metal:

:{{chem2|Pb + Cl2 → PbCl2}}

Addition of chloride ions to a suspension of PbCl₂ gives rise to soluble complex ions. In these reactions the additional chloride (or other ligands) break up the chloride bridges that comprise the polymeric framework of solid PbCl_2(s).

:PbCl_2(s) + Cl⁻ → [PbCl₃]⁻_(aq)

:PbCl_2(s) + 2 Cl⁻ → [PbCl₄]²⁻_(aq)

PbCl₂ reacts with molten NaNO₂ to give PbO:

:PbCl_2(l) + 3 NaNO₂ → PbO + NaNO₃ + 2 NO + 2 NaCl

PbCl₂ is used in synthesis of lead(IV) chloride (PbCl₄): Cl₂ is bubbled through a saturated solution of PbCl₂ in aqueous NH₄Cl forming [NH₄]₂[PbCl₆]. The latter is reacted with cold concentrated sulfuric acid (H₂SO₄) forming PbCl₄ as an oil.{{Housecroft2nd|page=365}}

Lead(II) chloride is the main precursor for organometallic derivatives of lead, such as plumbocenes.{{cite journal|last1 = Lowack|first1 = R|doi = 10.1016/0022-328X(94)84136-5|title = Decasubstituted decaphenylmetallocenes|year = 1994|pages = 25–32|volume = 476|journal = J. Organomet. Chem.|url = https://zenodo.org/record/1253944}} The usual alkylating agents are employed, including Grignard reagents and organolithium compounds:

:2 PbCl₂ + 4 RLi → R₄Pb + 4 LiCl + Pb

:2 PbCl₂ + 4 RMgBr → R₄Pb + Pb + 4 MgBrCl

:3 PbCl₂ + 6 RMgBr → R₃Pb-PbR₃ + Pb + 6 MgBrCl{{Housecroft2nd|page=524}}

These reactions produce derivatives that are more similar to organosilicon compounds, i.e. that Pb(II) tends to disproportionate upon alkylation.

PbCl₂ can be used to produce PbO₂ by treating it with sodium hypochlorite (NaClO), forming a reddish-brown precipitate of PbO₂.

• Molten PbCl₂ is used in the synthesis of lead titanate and barium lead titanate ceramics by cation replacement reactions:{{cite journal|last1 = Aboujalil|first1 = Almaz|last2 = Deloume|first2 = Jean-Pierre|last3 = Chassagneux|first3 = Fernand|last4 = Scharff|first4 = Jean-Pierre|last5 = Durand|first5 = Bernard|title = Molten salt synthesis of the lead titanate PbTiO₃, investigation of the reactivity of various titanium and lead salts with molten alkali-metal nitrites|journal = Journal of Materials Chemistry|volume = 8|pages = 1601|year = 1998|doi = 10.1039/a800003d|issue = 7}}
• :x PbCl_2(l) + BaTiO_3(s) → Ba_1−xPb_xTiO₃ + x BaCl₂
• PbCl₂ is used in production of infrared transmitting glass,Dictionary of Inorganic and Organometallic Compounds. Lead(II) Chloride.[http://www.chemnetbase.com] and ornamental glass called aurene glass. Aurene glass has an iridescent surface formed by spraying with PbCl₂ and reheating under controlled conditions. Stannous chloride (SnCl₂) is used for the same purpose.[http://www.thestorefinder.com/glass/library/terms/termsA.html Stained Glass Terms and Definitions. aurene glass]
• Pb is used in HCl service even though the PbCl₂ formed is slightly soluble in HCl. Addition of 6–25% of antimony (Sb) increases corrosion resistance.Kirk-Othmer. Encyclopedia of Chemical Technology. (ed 4). p 913
• A basic chloride of lead, PbCl₂·Pb(OH)₂, is known as Pattinson's white lead and is used as pigment in white paint.Perry & Phillips. Handbook of Inorganic Compounds. (1995). p 213 Lead paint is now banned as a health hazard in many countries by the White Lead (Painting) Convention, 1921.
• PbCl₂ is an intermediate in refining bismuth (Bi) ore. The ore containing Bi, Pb, and Zn is first treated with molten caustic soda to remove traces of arsenic and tellurium. This is followed by the Parkes process to remove any silver and gold present. There are now Bi, Pb, and Zn in the ore. At 500 °C, it receives treatment from Cl2 gas. First, ZnCl2 forms and is excreted. Pure Bi is left behind after PbCl2 forms and is eliminated. Lastly, BiCl3 would form.Kirk-Othmer. Encyclopedia of Chemical Technology. (ed 4). p. 241

Like other soluble lead compounds, exposure to PbCl₂ may cause lead poisoning.

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{{reflist|30em}}

{{Commons category|Lead(II) chloride}}

• [https://web.archive.org/web/20051012214505/http://www-cie.iarc.fr/htdocs/monographs/suppl7/leadandleadcompounds.html IARC Monograph: "Lead and Lead Compounds"]
• [https://web.archive.org/web/20051120060034/http://www-cie.iarc.fr/htdocs/announcements/vol87.htm IARC Monograph: "Inorganic and Organic Lead Compounds"]
• [https://web.archive.org/web/20080111154608/http://www.npi.gov.au/database/substance-info/profiles/50.html National Pollutant Inventory – Lead and Lead Compounds Fact Sheet]
• [https://www.atsdr.cdc.gov/csem/csem.html Case Studies in Environmental Medicine – Lead Toxicity]
• [https://www.atsdr.cdc.gov/toxfaqs/tfacts13.pdf ToxFAQs: Lead]

{{Lead compounds}}

{{Chlorides}}

Category:Lead(II) compounds

Category:Chlorides

Category:Metal halides

Category:IARC Group 2A carcinogens