:Tin(IV) chloride

It is prepared from reaction of chlorine gas with tin at {{convert|115|C|F}}:

:{{chem2|Sn + 2Cl2 → SnCl4}}

File:Tin(IV) chloride space-filling3D.png

File:SnCl4-xtal-down-b-axis-2005-CM-3D-polyhedra.png

Anhydrous tin(IV) chloride solidifies at −33 °C to give monoclinic crystals with the P21/c space group. It is isostructural with SnBr₄. The molecules adopt near-perfect tetrahedral symmetry with average Sn–Cl distances of 227.9(3) pm.{{cite journal |last=Reuter |first=Hans |author2=Pawlak, Rüdiger |title=Die Molekül- und Kristallstruktur von Zinn(IV)-chlorid |journal=Zeitschrift für anorganische und allgemeine Chemie |date=April 2000 |volume=626 |issue=4 |pages=925–929 |doi=10.1002/(SICI)1521-3749(200004)626:4<925::AID-ZAAC925>3.0.CO;2-R |language=German}}

Tin(IV) chloride is well known as a Lewis acid. Thus it forms hydrates. The pentahydrate SnCl₄·5H₂O was formerly known as butter of tin. These hydrates consist of cis-[SnCl₄(H₂O)₂] molecules together with varying amounts of water of crystallization. The additional water molecules link together the molecules of [SnCl₄(H₂O)₂] through hydrogen bonds. A pentahydrate has also been crystallized. In cis-{{chem2|SnCl4(H2O)2*3H2O}}, the Sn-Cl bonds are 238.3 pm.{{cite journal |doi=10.1039/dt9800000949 |title=Crystal Structures of di-µ-Hydroxo-bis[aquatrichlorotin (IV)]–1,4-dioxan (1/3), di-µ-hydroxo-bis[aquatrichlorotin(IV)]–1,8-epoxy-p-menthane (1/4), di-µ-hydroxo-bis[aquatribromotin (IV)]–1,8-epoxy-p-menthane (1/4), di-µ-hydroxo-bis[aquatrichlorotin(IV)]–water (1/4), and cis-Diaquatetrachlorotin (IV)–water (1/3) |date=1980 |last1=Barnes |first1=John C. |last2=Sampson |first2=Hazel A. |last3=Weakley |first3=Timothy J. R. |journal=J. Chem. Soc., Dalton Trans. |issue=6 |pages=949–953 }} Although the pentahydrate is the most common hydrate, lower hydrates have also been characterised.{{cite journal |last=Genge |first=Anthony R. J. |author2=Levason, William |author3=Patel, Rina |author4=Reid, Gillian |author5= Webster, Michael |display-authors=3 |title=Hydrates of tin tetrachloride |journal=Acta Crystallographica Section C |date=2004 |volume=60 |issue=4 |pages=i47–i49 |doi=10.1107/S0108270104005633 |pmid=15071197 |doi-access=free}}

Aside from water, other Lewis bases form adducts with SnCl₄. These include ammonia and organophosphines.

The ammonium salt of [SnCl₆]²⁻ is formed from ammonium chloride. It is called "pink salt":

:{{chem2|SnCl4 + 2 (NH4)Cl → (NH4)2SnCl6}}

The analogous reaction with hydrochloric acid gives "hexachlorostannic acid".

Reaction of the tetrachloride with hydrogen fluoride gives tin tetrafluoride:

:{{chem2|SnCl4 + 4 HF→ SnF4 + 4 HCl}}

Tin(IV) chloride undergoes redistribution with tin(IV) bromide as assessed by ¹¹⁹Sn NMR and Raman spectroscopy. Equilibrium is achieved in seconds at room temperature. By contrast, halide exchange for related germanium and especially silicon halides is slower.{{cite journal |doi=10.1021/cr60233a004 |title=Redistribution and Exchange Reactions in Groups IIB-VIIB |date=1965 |last1=Lockhart |first1=J. C. |journal=Chemical Reviews |volume=65 |pages=131–151 }}

Anhydrous tin(IV) chloride is a major precursor in organotin chemistry. Upon treatment with Grignard reagents, tin(IV) chloride gives tetraalkyltin compounds:{{Greenwood&Earnshaw}}

:SnCl₄ + 4 RMgCl → SnR₄ + 4 MgCl₂

Anhydrous tin(IV) chloride reacts with tetraorganotin compounds in redistribution reactions:

:SnCl₄ + SnR₄ → 2 SnCl₂R₂

These organotin halides are useful precursors to catalysts (e.g., dibutyltin dilaurate) and polymer stabilizers.G. G. Graf "Tin, Tin Alloys, and Tin Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2005 Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a27_049}}

SnCl₄ is used in Friedel–Crafts reactions as a Lewis acid catalyst. For example, the acetylation of thiophene to give 2-acetylthiophene is promoted by tin(IV) chloride.{{cite journal |author=John R. Johnson, G. E. May|doi=10.15227/orgsyn.018.0001|title=2-Acetothienone|journal=Organic Syntheses|year=1938|volume=18|page=1}} Similarly, tin(IV) chloride is useful for nitrations.{{cite journal | journal = Synthesis | year = 1990 | pages = 81–84 | doi = 10.1055/s-1990-26795 | title = O-Debenzylation of a Pyrrolo[2,1-c][1,4]benzodiazepine in the Presence of a Carbinolamine Functionality: Synthesis of DC-81 | author = Thurston, David E. | volume = 1990 | last2 = Murty | first2 = Varanasi S. | last3 = Langley | first3 = David R. | last4 = Jones | first4 = Gary B.| s2cid = 98109571 }}

Stannic chloride was used as a chemical weapon in World War I, as it formed an irritating (but non-deadly) dense smoke on contact with air. It was supplanted by a mixture of silicon tetrachloride and titanium tetrachloride near the end of the war due to shortages of tin.{{Cite book | pages = 148–49, 407 | title = Chemical Warfare | first = Amos A. | last = Fries | publisher = Read | year = 2008 | isbn = 978-1-4437-3840-8 }}.

{{reflist}}

{{Commons category|Tin(IV) chloride}}

• [https://www.inchem.org/documents/icsc/icsc/eics0953.htm International Chemical Safety Card 0953]
• {{Webarchive |url=https://web.archive.org/web/20050228231850/http://www.tinchemical.com/products.html |date=2005-02-28 |title=tinchemical.com/products (industrial uses) |nolink=1}}

{{Tin compounds}}

{{Chlorides}}

Category:Chlorides

Category:Tin(IV) compounds

Category:Metal halides