Chalcogenide

<h2 id="alkali-metal-and-alkaline-earth-chalcogenides">Alkali metal and alkaline earth chalcogenides</h2>
<p>Alkali metal and alkaline earth monochalcogenides are salt-like, being colourless and often water-soluble. The sulfides tend to undergo hydrolysis to form derivatives containing <a href="/facts/Bisulfide/xIwK8as1">bisulfide</a> (SH−) anions. The alkali metal chalcogenides often crystallize with the anti<a href="/facts/Fluorite/y2G7C8zk">fluorite</a> structure and the alkaline earth salts in the <a href="/facts/Sodium_chloride/MWcXl3Mb">sodium chloride</a> motif.
</p>

<h2 id="transition-metal-chalcogenides">Transition metal chalcogenides</h2>
<p>Transition metal chalcogenides occur with many stoichiometries and many structures.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> Most common and most important technologically, however, are the chalcogenides of simple stoichiometries, such as 1:1 and 1:2. Extreme cases include metal-rich phases (e.g. Ta2S), which exhibit extensive metal-metal bonding,<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> and chalcogenide-rich materials such as Re2S7, which features extensive chalcogen-chalcogen bonding.
</p><p>For the purpose of classifying these materials, the chalcogenide is often viewed as a dianion, i.e., <a href="/facts/Sulfide/d8YMjLeu">S2−</a>, <a href="/facts/Selenide/vA9Ls4xH">Se2−</a>, <a href="/facts/Telluride_(chemistry)/r8gVazKR">Te2−</a>, and <a href="/facts/Polonide/nT9RtKx5">Po2−</a>. In fact, transition metal chalcogenides are highly <a href="/facts/Covalent/EzMLf3Pz">covalent</a>, not ionic, as indicated by their semiconducting properties.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a>
</p>
<h3>Metal-rich chalcogenides</h3>

<p>In most of their chalcogenides, transition metals adopt oxidation states of II or greater. Nonetheless, several examples exist where the metallic atoms far outnumber the chalcogens. Such compounds typically have extensive metal-metal bonding.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a>
</p>
<h3>Monochalcogenides</h3>
<p>Metal monochalcogenides have the formula ME, where M = a transition metal and E = S, Se, Te. They typically crystallize in one of two motifs, named after the corresponding forms of <a href="/facts/Zinc_sulfide/K8l5AF3K">zinc sulfide</a>. In the <a href="/facts/Zinc_blende/5NumvnzR">zinc blende</a> structure, the sulfide atoms pack in a cubic symmetry and the Zn2+ ions occupy half of the tetrahedral holes. The result is a <a href="/facts/Diamondoid/HQXKwNwL">diamondoid</a> framework. The main alternative structure for the monochalcogenides is the <a href="/facts/Wurtzite/QPwdFcCx">wurtzite</a> structure wherein the atom connectivities are similar (tetrahedral), but the crystal symmetry is hexagonal. A third motif for metal monochalcogenide is the <a href="/facts/Nickel_arsenide/fbXdeD92">nickel arsenide</a> lattice, where the metal and chalcogenide each have octahedral and trigonal prismatic coordination, respectively. This motif is commonly subject to <a href="/facts/Nonstoichiometry/DAssoN0e">nonstoichiometry</a>.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a>
</p><p>Important monochalcogenides include some <a href="/facts/Pigment/I3clCYkF">pigments</a>, notably <a href="/facts/Cadmium_sulfide/lsYV3Gum">cadmium sulfide</a>. Many minerals and ores are monosulfides.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a>
</p>
<h3>Dichalcogenides</h3>
<p>Metal dichalcogenides have the formula ME2, where M = a transition metal and E = S, Se, Te.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> The most important members are the sulfides. They are always dark diamagnetic solids, insoluble in all solvents, and exhibit <a href="/facts/Semiconductor/zFf3mGTE">semiconducting</a> properties. Some are <a href="/facts/Superconductivity/pqQAlSzJ">superconductors</a>.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a>
</p><p>In terms of their electronic structures, these compounds are usually viewed as derivatives of M4+, where M4+ = Ti4+ (d0 configuration), V4+ (d1 configuration), Mo4+ (d2 configuration). <a href="/facts/Titanium_disulfide/dT6VxH16">Titanium disulfide</a> was investigated in prototype <a href="/facts/Cathode/tqdlGayU">cathodes</a> for secondary batteries, exploiting its ability to reversibly undergo <a href="/facts/Intercalation_(chemistry)/YsayFumX">intercalation</a> by <a href="/facts/Lithium/7vXX6BWA">lithium</a>. Molybdenum disulfide is the subject of thousands of articles and the main ore of molybdenum, termed <a href="/facts/Molybdenite/jatlEkxR">molybdenite</a>. It is used as a <a href="/facts/Solid_lubricant/N4GgvV41">solid lubricant</a> and catalyst for <a href="/facts/Hydrodesulfurization/CTXmxBQu">hydrodesulfurization</a>. The corresponding diselenides and even ditellurides are known, e.g., <a href="/facts/Titanium_diselenide/3200r1xD">TiSe2</a>, <a href="/facts/Molybdenum_diselenide/fzAc3TxR">MoSe2</a>, and <a href="/facts/Tungsten_diselenide/hMXEh4gY">WSe2</a>.
</p>
<h3>Transition metals</h3>
<p>Transition metal dichalcogenides typically adopt either <a href="/facts/Cadmium_diiodide/kmYqUThz">cadmium diiodide</a> or <a href="/facts/Molybdenum_disulfide/4TRft6Ua">molybdenum disulfide</a> structures. In the CdI2 motif, the metals exhibit octahedral structures. In the MoS2 motif, which is not observed for dihalides, the metals exhibit trigonal prismatic structures.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> The strong bonding between the metal and chalcogenide ligands, contrasts with the weak chalcogenide—chalcogenide bonding between the layers. Owing to these contrasting bond strengths, these materials engage in <a href="/facts/Intercalation_(chemistry)/YsayFumX">intercalation</a> by <a href="/facts/Alkali_metals/IkWbCLk2">alkali metals</a>. The intercalation process is accompanied by charge transfer, reducing the M(IV) centers to M(III). The attraction between electrons and holes in 2D tungsten diselenide is 100s of times stronger than in a typical 3D semiconductor.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a>
</p>
<h4>Pyrite and related disulfides</h4>
<p>In contrast to classical metal dichalcogenides, <a href="/facts/Iron_pyrite/41CYREyr">iron pyrite</a>, a common mineral, is usually described as consisting of Fe2+ and the persulfido anion S22−. The sulfur atoms within the persulfido dianion are bound together via a short S-S bond.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> "Late" transition metal disulfides (Mn, Fe, Co, Ni) almost always adopt the pyrite or the related <a href="/facts/Marcasite/vP4CW3QC">marcasite</a> motif, in contrast to early metals (V, Ti, Mo, W) which adopt 4+ oxidation state with two chalcogenide dianions.
</p>
<h3>Tri- and tetrachalcogenides</h3>
<p>Several metals, mainly for the early metals (Ti, V, Cr, Mn groups) also form trichalcogenides. These materials are usually described as M4+(E22−)(E2−) (where E = S, Se, Te). A well known example is <a href="/facts/Niobium_triselenide/hr4aveoM">niobium triselenide</a>. Amorphous MoS3 is produced by treatment of <a href="/facts/Tetrathiomolybdate/Nw1N4DX3">tetrathiomolybdate</a> with acid:
</p>
MoS42− + 2 H+ → MoS3 + H2S
<p>The mineral <a href="/facts/Patr%25C3%25B3nite/hcosFGuN">patrónite</a>, which has the formula VS4, is an example of a metal tetrachalcogenide. Crystallographic analysis shows that the material can be considered a bis(persulfide), i.e. V4+,(S22−)2.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a>
</p>
<h2 id="main-group-chalcogenides">Main group chalcogenides</h2>

<p>Chalcogen derivatives are known for all of the <a href="/facts/Main_group_element/2AG3QxJl">main group elements</a> except the noble gases. Usually, their stoichiometries follow the classical valence trends, e.g. <a href="/facts/Silicon_disulfide/NsydQecc">SiS2</a>, <a href="/facts/Boron_sulfide/8ncsn4CP">B2S3</a>, <a href="/facts/Antimony_trisulfide/Y9q8h4c7">Sb2S3</a>. Many exceptions exist however, e.g. <a href="/facts/Phosphorus_sesquisulfide/6TPdHbVX">P4S3</a> and <a href="/facts/S4N4/1ojDg4Yj">S4N4</a>. The structures of many main group materials are dictated by directional covalent bonding, rather than by close packing.<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a>
</p><p>The chalcogen is assigned positive oxidation states for the halides, nitrides, and oxides.
</p>
<h2 id="see-also">See also</h2>
<ul><li>Carbon dichalcogenide</li>
<li><a href="/facts/Chalcogen/nXLGmnqL">Chalcogen</a></li>
<li><a href="/facts/Chalcogenide_glass/6Lug8YLy">Chalcogenide glass</a></li>
<li><a href="/facts/Hydrogen_chalcogenide/pNCrhmwX">Hydrogen chalcogenide</a></li>
<li><a href="/facts/Negative_resistance/QgkR8esF">Negative resistance</a></li>
<li><a href="/facts/Phase-change_memory/jeMTI5RI">Phase-change memory</a></li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="http://actalab.com">Advanced Chalcogenide Technologies and Applications Lab</a> <i>ACTAlab</i> Jun 14, 2016</li>
<li><a href="http://scienceblog.com/45604/phase-change-memory-based-monetasystem-points-to-the-future-of-computer-storage/">Phase change memory-based 'moneta' system points to the future of computer storage</a> <i>ScienceBlog</i> Jun 03, 2011</li>
<li>Kovalenko, Maksym V.; Scheele, Marcus; Talapin, Dmitri V. (2009). "Colloidal Nanocrystals with Molecular Metal Chalcogenide Surface Ligands". <i>Science</i>. 324 (5933): 1417–1420. <a href="/facts/Bibcode_(identifier)/9HtdQSGB">Bibcode</a>:<a href="https://ui.adsabs.harvard.edu/abs/2009Sci...324.1417K">2009Sci...324.1417K</a>. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1126%2Fscience.1170524">10.1126/science.1170524</a>. <a href="/facts/PMID_(identifier)/JlHAvMHt">PMID</a> <a href="https://pubmed.ncbi.nlm.nih.gov/19520953">19520953</a>. <a href="/facts/S2CID_(identifier)/ldJsHa2Y">S2CID</a> <a href="https://api.semanticscholar.org/CorpusID:21845356">21845356</a>.</li>
<li><a href="https://www.theregister.co.uk/2010/02/12/earth_abundant_solar_cells/">Big Blue boffins hatch dirt-cheap solar cells</a> The Register, 12 February 2010</li></ul>

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

<ol>
<li id="fn:1"><p>Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Vaughan, D. J.; Craig, J. R. "Mineral Chemistry of Metal Sulfides" Cambridge University Press, Cambridge: 1978. ISBN 0-521-21489-0. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Hughbanks, Timothy (1995). "Exploring the metal-rich chemistry of the early transition elements". Journal of Alloys and Compounds. 229: 40–53. doi:10.1016/0925-8388(95)01688-0. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Vaughan, D. J.; Craig, J. R. "Mineral Chemistry of Metal Sulfides" Cambridge University Press, Cambridge: 1978. ISBN 0-521-21489-0. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>Franzen, Hugo F. (1978). "Structure and Bonding of Metal-Rich Compounds: Pnictides, chalcogenides and halides". Progress in Solid State Chemistry. 12: 1–39. doi:10.1016/0079-6786(78)90002-X. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>"Sulfide Mineralogy: Volume 1" Paul H. Ribbe, editor, 1974, Mineralogical Society of America. ISBN 0-939950-01-4 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
<li id="fn:9"><p>Wood, Charlie (2022-08-16). "Physics Duo Finds Magic in Two Dimensions". Quanta Magazine. Retrieved 2022-08-22. <a href="https://www.quantamagazine.org/physics-duo-finds-magic-in-two-dimensions-20220816/" target="_blank">https://www.quantamagazine.org/physics-duo-finds-magic-in-two-dimensions-20220816/</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li>
<li id="fn:10"><p>Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li>
<li id="fn:11"><p>Wood, Charlie (2022-08-16). "Physics Duo Finds Magic in Two Dimensions". Quanta Magazine. Retrieved 2022-08-22. <a href="https://www.quantamagazine.org/physics-duo-finds-magic-in-two-dimensions-20220816/" target="_blank">https://www.quantamagazine.org/physics-duo-finds-magic-in-two-dimensions-20220816/</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li>
<li id="fn:12"><p>Vaughan, D. J.; Craig, J. R. "Mineral Chemistry of Metal Sulfides" Cambridge University Press, Cambridge: 1978. ISBN 0-521-21489-0. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li>
<li id="fn:13"><p>Vaughan, D. J.; Craig, J. R. "Mineral Chemistry of Metal Sulfides" Cambridge University Press, Cambridge: 1978. ISBN 0-521-21489-0. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li>
<li id="fn:14"><p>Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4. <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li>
</ol>

Chalcogenide open-in-new

Chalcogenide