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Zirconium(IV) chloride



Zirconium(IV) chloride
Other names Zirconium tetrachloride
Identifiers
CAS number 10026-11-6
EINECS number 233-058-2
Properties
Molecular formula ZrCl4
Molar mass 233.04 g/mol
Boiling point

331°C subl.

Solubility in other solvents hydrolysis in water
soluble in alcohol
Thermochemistry
Std enthalpy of
formation
ΔfHo298
-980.52 kJ/mol
Standard molar
entropy
So298
181.41 J.K–1.mol–1
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Zirconium(IV) chloride, also known as zirconium tetrachloride, is the inorganic compound with the formula ZrCl4. This white high-melting solid hydrolyzes rapidly in humid air. It is a key reagent in the chemistry of zirconium.

Additional recommended knowledge

Contents

Structure

Unlike TiCl4, ZrCl4 adopts a polymeric structure wherein each Zr is octahedrally coordinated. This difference in structures, polymeric vs. molecular, is responsible for the striking difference in their properties - one being distillable, the other being a high melting solid. In the solid state, ZrCl4 adopts a tape-like linear polymeric structure--the same structure adopted by HfCl4. This polymer degrades readily upon treatment with Lewis bases, which cleave the Zr-Cl-Zr linkages.[1]

Kroll process

ZrCl4 is an intermediate in the conversion of zirconium minerals to metallic zirconium by the Kroll process. In nature, zirconium minerals invaribly exists as oxides (reflected also by the tendency of all zirconium chlorides to hydrolyze). For their conversion to bulk metal, these refractory oxides are first converted to the tetrachloride, which can be distilled at high temperatures. This conversion entails treatment of the oxide with carbon as the oxide "getter" and chlorine.

ZrO2 + 2 C + 2 Cl2 → ZrCl4 + 2 CO

Chemical reactions

ZrCl4 is the principal starting compound for the synthesis of many organometallic complexes of zironcium.[2] Because of its polymeric structure, ZrCl4 it is usually converted to a molecular complex before use. It forms a 1:2 complex with tetrahydrofuran: CAS [21959-01-3], mp 175-177 °C.[3] NaC5H5 reacts with ZrCl4(THF)2 to give zirconocene dichloride, ZrCl2(C5H5)2, a versatile organozirconium complex.[4] One of the most curious properties of ZrCl4 is its high solubility in the presence of methylated benzenes, such as durene. This solubilization arises through the formation of π-complexes.[5]

Uses

In organic synthesis zirconium tetrachloride is used as a weak Lewis acid for the Friedel-Crafts reaction, the Diels-Alder reaction and intramolecular cyclisation reactions.[6] It is also used to make water-repellent textiles.


References

  1. ^ N. N. Greenwood & A. Earnshaw, Chemistry of the Elements (2nd ed.), Butterworth-Heinemann, Oxford, 1997.
  2. ^ New Aspects of Zirconium Containing Organic Compounds. Topics in Organometallic Chemistry, 10 Edited by Ilan Marek (Technion-Israel Institute of Technology, Haifa). Springer: Berlin, Heidelberg, New York. 2005. x + 176 pp. ISBN 3-540-22221-9.
  3. ^ L. E. Manxzer, Joe Deaton, Paul Sharp, R. R. Schrock (1982). "Tetrahydrofuran Complexes of Selected Early Transition Metals". Inorganic Syntheses 21: 135-40. doi:10.1002/9780470132524.ch31.
  4. ^ G. Wilkinson and J.G. Birmingham (1954). "Bis-cyclopentadienyl Compounds of Ti, Zr, V, Nb and Ta". J. Am. Chem. Soc. 76 (17): 4281-4284. doi:10.1021/ja01646a008.
  5. ^ Musso, F.; Solari, E.; Floriani, C.; Schenk, K. (1997). "Hydrocarbon Activation with Metal Halides: Zirconium Tetrachloride Catalyzing the Jacobsen Reaction and Assisting the Trimerization of Alkynes via the Formation of η6-Arene-Zirconium(IV) Complexes". Organometallics 16: 4889-4895. doi:10.1021/om970438g.
  6. ^ Bora U. (2003). "Zirconium Tetrachloride". Synlett: 1073-1074. doi:10.1055/s-2003-39323.
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Zirconium(IV)_chloride". A list of authors is available in Wikipedia.
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