Zinc iodide

<h2 id="preparation">Preparation</h2>
It can be prepared by the direct reaction of zinc and iodine in water<a class="footnote-ref" id="fnref:1" href="#fn:1">1</a><a class="footnote-ref" id="fnref:2" href="#fn:2">2</a> or refluxing <a href="/facts/Diethyl_ether/Ep20vEdj">ether</a>:<a class="footnote-ref" id="fnref:3" href="#fn:3">3</a>

Zn + I2 → ZnI2
Absent a solvent, the elements do not combine directly at room temperature.<a class="footnote-ref" id="fnref:4" href="#fn:4">4</a>

<h2 id="structure-as-solid-gas-and-in-solution">Structure as solid, gas, and in solution</h2>
The structure of solid ZnI2 is unusual relative to the dichloride. While zinc centers are tetrahedrally coordinated, as in <a href="/facts/Zinc_chloride/aYscGQL7">ZnCl2</a>, groups of four of these tetrahedra share three vertices to form “super-tetrahedra” of composition {Zn4I10}, which are linked by their vertices to form a three-dimensional structure.<a class="footnote-ref" id="fnref:5" href="#fn:5">5</a> These "super-tetrahedra" are similar to the <a href="/facts/Phosphorus_pentoxide/GKTSUNqS">P4O10</a> structure.<a class="footnote-ref" id="fnref:6" href="#fn:6">6</a><a class="footnote-ref" id="fnref:7" href="#fn:7">7</a>
Molecular ZnI2 is linear as predicted by <a href="/facts/VSEPR/WqsRgVRV">VSEPR</a> theory with a Zn-I bond length of 238 pm.<a class="footnote-ref" id="fnref:8" href="#fn:8">8</a>
In aqueous solution the following have been detected: Zn(H2O)62+, [ZnI(H2O)5]+, tetrahedral ZnI2(H2O)2, ZnI3(H2O)−, and ZnI42−.<a class="footnote-ref" id="fnref:9" href="#fn:9">9</a>

<h2 id="applications">Applications</h2>
<ul><li>Zinc iodide is often used as an <a href="/facts/X-ray/wseP79cN">x-ray</a> <a href="/facts/Opacity_(optics)/l90q0sAV">opaque</a> penetrant in <a href="/facts/Industrial_radiography/q9cEdMFP">industrial radiography</a> to improve the contrast between the damage and intact composite.<a class="footnote-ref" id="fnref:10" href="#fn:10">10</a><a class="footnote-ref" id="fnref:11" href="#fn:11">11</a></li>
<li>United States <a href="/facts/Patent/LjT2bG3A">patent</a> 4,109,065 <a class="footnote-ref" id="fnref:12" href="#fn:12">12</a> describes a rechargeable aqueous zinc-halogen <a href="/facts/Electrochemical_cell/o7oEnYVl">cell</a> that includes an aqueous electrolytic solution containing a zinc salt selected from the class consisting of <a href="/facts/Zinc_bromide/JnqEoDcI">zinc bromide</a>, zinc iodide, and mixtures thereof, in both positive and negative <a href="/facts/Electrode/251PaKX8">electrode</a> compartments.</li>
<li>In combination with <a href="/facts/Osmium_tetroxide/cxmYVnFK">osmium tetroxide</a>, ZnI2 is used as a stain in electron microscopy.<a class="footnote-ref" id="fnref:13" href="#fn:13">13</a></li>
<li>As a Lewis acid, zinc iodide catalyzes for the conversion of <a href="/facts/Methanol/EIfpoNCg">methanol</a> to <a href="/facts/Triptane/P9u4nwks">triptane</a> and <a href="/facts/Hexamethylbenzene/IX3rWv20">hexamethylbenzene</a>.<a class="footnote-ref" id="fnref:14" href="#fn:14">14</a></li>
<li>It can be used as a topical antiseptic.<a class="footnote-ref" id="fnref:15" href="#fn:15">15</a></li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1">F. Wagenknecht; R. Juza (1963). "Zinc iodide". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 1. NY, NY: Academic Press. p. 1073. <a href="#fnref:1" class="footnote-back-ref">↩</a></li>
<li id="fn:2">DeMeo, S. (1995). "Synthesis and Decomposition of Zinc Iodide: Model Reactions for Investigating Chemical Change in the Introductory Laboratory". Journal of Chemical Education. 72 (9): 836. Bibcode:1995JChEd..72..836D. doi:10.1021/ed072p836. <a href="https://pubs.acs.org/doi/abs/10.1021/ed072p836" target="_blank">https://pubs.acs.org/doi/abs/10.1021/ed072p836</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></li>
<li id="fn:3">Eagleson, M. (1994). Concise Encyclopedia Chemistry. Walter de Gruyter. ISBN 3-11-011451-8. <a href="3-11-011451-8" target="_blank">3-11-011451-8</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></li>
<li id="fn:4">Gilbert, George; Houston, Kelly; Jacobsen, Jerrold J.; Phillips, David (2022) [6 Mar 2012]. Zinc iodine reaction (web video). American Chemical Society, Division of Chemical Education – via ChemEdX. <a href="https://www.chemedx.org/video/zinc-iodine-reaction" target="_blank">https://www.chemedx.org/video/zinc-iodine-reaction</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></li>
<li id="fn:5">Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford Science Publications. ISBN 0-19-855370-6. <a href="0-19-855370-6" target="_blank">0-19-855370-6</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></li>
<li id="fn:6">Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford Science Publications. ISBN 0-19-855370-6. <a href="0-19-855370-6" target="_blank">0-19-855370-6</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></li>
<li id="fn:7">Fourcroy, P. H.; Carré, D.; Rivet, J. (1978). "Structure Cristalline de l'Iodure de Zinc ZnI2". Acta Crystallographica Section B: Structural Crystallography and Crystal Chemistry. 34 (11): 3160–3162. Bibcode:1978AcCrB..34.3160F. doi:10.1107/S0567740878010390. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></li>
<li id="fn:8">Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford Science Publications. ISBN 0-19-855370-6. <a href="0-19-855370-6" target="_blank">0-19-855370-6</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></li>
<li id="fn:9">Wakita, H.; Johansson, G.; Sandström, M.; Goggin, P. L.; Ohtaki, H. (1991). "Structure determination of zinc iodide complexes formed in aqueous solution". Journal of Solution Chemistry. 20 (7): 643–668. doi:10.1007/BF00650714. S2CID 97496242. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></li>
<li id="fn:10">Baker, A.; Dutton, S.; Kelly, D., eds. (2004). Composite Materials for Aircraft Structures (2nd ed.). AIAA (American Institute of Aeronautics & Astronautics). ISBN 1-56347-540-5. <a href="1-56347-540-5" target="_blank">1-56347-540-5</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></li>
<li id="fn:11">Ezrin, M. (1996). Plastics Failure Guide. Hanser Gardner Publications. ISBN 1-56990-184-8. <a href="1-56990-184-8" target="_blank">1-56990-184-8</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></li>
<li id="fn:12">US patent 4109065, Will, F. G.; Secor, F. W., "Rechargeable aqueous zinc-halogen cell", issued 1978-08-22, assigned to General Electric
 <a href="https://worldwide.espacenet.com/textdoc?DB=EPODOC&IDX=US4109065" target="_blank">https://worldwide.espacenet.com/textdoc?DB=EPODOC&IDX=US4109065</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></li>
<li id="fn:13">Hayat, M. A. (2000). Principles and Techniques of Electron Microscopy: Biological Applications (4th ed.). Cambridge University Press. ISBN 0-521-63287-0. <a href="0-521-63287-0" target="_blank">0-521-63287-0</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></li>
<li id="fn:14">Bercaw, John E.; Diaconescu, Paula L.; Grubbs, Robert H.; Kay, Richard D.; Kitching, Sarah; Labinger, Jay A.; Li, Xingwei; Mehrkhodavandi, Parisa; Morris, George E. (2006-11-01). "On the Mechanism of the Conversion of Methanol to 2,2,3-Trimethylbutane (Triptane) over Zinc Iodide". The Journal of Organic Chemistry. 71 (23): 8907–8917. doi:10.1021/jo0617823. ISSN 0022-3263. PMID 17081022. <a href="/wiki/Paula_Diaconescu" target="_blank">/wiki/Paula_Diaconescu</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></li>
<li id="fn:15">Rohe, Dieter M. M.; Wolf, Hans Uwe (2007), "Zinc Compounds", Ullmann's Encyclopedia of Industrial Chemistry (7th ed.), Wiley, pp. 1–6, doi:10.1002/14356007.a28_537, ISBN 978-3527306732 <a href="978-3527306732" target="_blank">978-3527306732</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></li>
</ol>

Zinc iodide open-in-new

Zinc iodide