<span class="mw-page-title-main">Pentamethylcyclopentadiene</span>

Pentamethylcyclopentadiene

<p><b>1,2,3,4,5-Pentamethylcyclopentadiene</b> is a <a href="/en/Cyclic_compound" title="Cyclic compound" class="wl">cyclic</a> <a href="/en/Diene" title="Diene" class="wl">diene</a> with the formula C<sub>5</sub>Me<sub>5</sub>H (Me = CH<sub>3</sub>).<span class="mw-ref reference" id="cite_ref-1"><a href="#cite_note-1" style="counter-reset: mw-Ref 1;"><span class="mw-reflink-text">[1]</span></a></span>  1,2,3,4,5-Pentamethylcyclopentadiene is the precursor to the <a href="/en/Ligand" title="Ligand" class="wl">ligand</a> <i>1,2,3,4,5-pentamethylcyclopentadienyl</i>, which is often denoted <b>Cp*</b> (C<sub>5</sub>Me<sub>5</sub>) and read as "C P star", the "star" signifying the five methyl groups radiating from the core of the ligand. In contrast to less-substituted <a href="/en/Cyclopentadiene" title="Cyclopentadiene" class="wl">cyclopentadiene</a> derivatives, Cp*H is not prone to dimerization.</p>

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</span><div class='mobile-collapse'><header class="mobile-collapse-header mobile-collapse-btn"><b>Quick facts: Names, Identifiers, Properties, Hazards...</b> <span class='arrow'>▼</span></header> <table class="infobox ib-chembox mobile-collapse-element"> 
<caption>Pentamethylcyclopentadiene</caption>
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<td colspan="2" style="text-align:center; padding:2px;"><span><a href="/en/File:Pentamethylcyclopentadien.svg" class="mw-file-description image media-thumb" data-hash="File:Pentamethylcyclopentadien.svg"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/c/cb/Pentamethylcyclopentadien.svg/135px-Pentamethylcyclopentadien.svg.png" decoding="async" data-file-width="260" data-file-height="249" data-file-type="drawing" height="129" width="135" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/c/cb/Pentamethylcyclopentadien.svg/203px-Pentamethylcyclopentadien.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/c/cb/Pentamethylcyclopentadien.svg/270px-Pentamethylcyclopentadien.svg.png 2x" alt="Pentamethylcyclopentadien.svg"></a></span></td></tr>
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<td colspan="2" style="text-align:center; padding:2px;"><span><a href="/en/File:Pentamethylcyclopentadiene_molecule_ball.png" class="mw-file-description image media-thumb" data-hash="File:Pentamethylcyclopentadiene_molecule_ball.png"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Pentamethylcyclopentadiene_molecule_ball.png/160px-Pentamethylcyclopentadiene_molecule_ball.png" decoding="async" data-file-width="2000" data-file-height="1871" data-file-type="bitmap" height="150" width="160" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Pentamethylcyclopentadiene_molecule_ball.png/240px-Pentamethylcyclopentadiene_molecule_ball.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/e/e1/Pentamethylcyclopentadiene_molecule_ball.png/320px-Pentamethylcyclopentadiene_molecule_ball.png 2x" alt="Pentamethylcyclopentadiene_molecule_ball.png"></a></span></td></tr>
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<th colspan="2" style="background: #f8eaba; text-align: center;" class="notheme">Names</th></tr>

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<td colspan="2" style="text-align:left;"><a href="/en/Preferred_IUPAC_name" title="Preferred IUPAC name" class="wl">Preferred IUPAC name</a>
<div style="max-width:22em; word-wrap:break-word; padding-left:1.7em;"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;max-width:22em;">1,2,3,4,5-Pentamethylcyclopenta-1,3-diene</div></div></td></tr>

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<th colspan="2" style="background: #f8eaba; text-align: center;" class="notheme">Identifiers</th></tr>

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<td><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;"><a href="/en/CAS_Registry_Number" title="CAS Registry Number" class="wl">CAS Number</a></div></td>
<td><style data-mw-deduplicate="TemplateStyles:r1126788409" typeof="mw:Extension/templatestyles">.mw-parser-output .plainlist ol,.mw-parser-output .plainlist ul{line-height:inherit;list-style:none;margin:0;padding:0}.mw-parser-output .plainlist ol li,.mw-parser-output .plainlist ul li{margin-bottom:0}</style><div class="plainlist"><ul><li><span><a rel="mw:ExtLink nofollow" href="https://commonchemistry.cas.org/detail?cas_rn=4045-44-7" class="external text" target="_blank">4045-44-7</a></span><sup><span>&nbsp;</span><span><span><img loading="lazy" src="//upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/7px-Yes_check.svg.png" decoding="async" data-file-width="600" data-file-height="600" data-file-type="drawing" height="7" width="7" srcset="//upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/11px-Yes_check.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/14px-Yes_check.svg.png 2x" alt="Yes_check.svg"></span></span><span style="display:none">Y</span></sup></li></ul></div></td></tr>

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<td><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">3D model (<a href="/en/JSmol" title="JSmol" class="mw-redirect wl">JSmol</a>)</div></td>
<td><div class="plainlist"><ul><li><span><a rel="mw:ExtLink nofollow" href="https://chemapps.stolaf.edu/jmol/jmol.php?model=CC1%3DC%28C%29C%28C%29C%28C%29%3DC1C" class="external text" target="_blank">Interactive image</a></span></li></ul></div></td></tr>

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<td><a href="/en/ChemSpider" title="ChemSpider" class="wl">ChemSpider</a></td>
<td><div class="plainlist"><ul><li><span><a rel="mw:ExtLink nofollow" href="https://www.chemspider.com/Chemical-Structure.70069.html" class="external text" target="_blank">70069</a></span><sup><span>&nbsp;</span><span><span><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/7px-X_mark.svg.png" decoding="async" data-file-width="525" data-file-height="600" data-file-type="drawing" height="8" width="7" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/11px-X_mark.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/14px-X_mark.svg.png 2x" alt="X_mark.svg"></span></span><span style="display:none">N</span></sup></li></ul></div></td></tr>

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<td><a href="/en/ECHA_InfoCard" title="ECHA InfoCard" class="mw-redirect wl"><span>ECHA InfoCard</span></a></td>
<td><a rel="mw:ExtLink nofollow" href="https://echa.europa.eu/substance-information/-/substanceinfo/100.021.586" class="external text" target="_blank">100.021.586</a> <span class="mw-valign-text-top noprint"><a href="/en/Q1927394#P2566" title="Edit this at Wikidata" class="image wl"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/10px-OOjs_UI_icon_edit-ltr-progressive.svg.png" decoding="async" data-file-width="20" data-file-height="20" data-file-type="drawing" height="10" width="10" srcset="//upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/15px-OOjs_UI_icon_edit-ltr-progressive.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/20px-OOjs_UI_icon_edit-ltr-progressive.svg.png 2x" alt="OOjs_UI_icon_edit-ltr-progressive.svg"></a></span></td></tr>
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<td><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;"><a href="/en/PubChem" title="PubChem" class="wl">PubChem</a> <abbr about="#mwt24" typeof="mw:ExpandedAttrs" data-mw="{&quot;attribs&quot;:[[{&quot;txt&quot;:&quot;title&quot;},{&quot;html&quot;:&quot;<span typeof=\&quot;mw:Nowiki\&quot; data-parsoid=\&quot;{}\&quot;>Compound ID</span>&quot;}]]}">CID</abbr></div></td>
<td><div class="plainlist"><ul><li><span><a rel="mw:ExtLink nofollow" href="https://pubchem.ncbi.nlm.nih.gov/compound/77667" class="external text" target="_blank">77667</a></span></li></ul></div></td></tr>

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<td><a href="/en/Unique_Ingredient_Identifier" title="Unique Ingredient Identifier" class="wl">UNII</a></td>
<td><div class="plainlist"><ul><li><span><a rel="mw:ExtLink nofollow" href="https://precision.fda.gov/uniisearch/srs/unii/DSE3MRZ77C" class="external text" target="_blank">DSE3MRZ77C</a></span><sup><span>&nbsp;</span><span><span><img loading="lazy" src="//upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/7px-Yes_check.svg.png" decoding="async" data-file-width="600" data-file-height="600" data-file-type="drawing" height="7" width="7" srcset="//upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/11px-Yes_check.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/14px-Yes_check.svg.png 2x" alt="Yes_check.svg"></span></span><span style="display:none">Y</span></sup></li></ul></div></td></tr>

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<td><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;"><a href="/en/CompTox_Chemicals_Dashboard" title="CompTox Chemicals Dashboard" class="wl">CompTox Dashboard</a> <span style="font-weight:normal">(<abbr about="#mwt25" typeof="mw:ExpandedAttrs" data-mw="{&quot;attribs&quot;:[[{&quot;txt&quot;:&quot;title&quot;},{&quot;html&quot;:&quot;<span typeof=\&quot;mw:Nowiki\&quot; data-parsoid=\&quot;{}\&quot;>U.S. Environmental Protection Agency</span>&quot;}]]}">EPA</abbr>)</span></div></td>
<td><div class="plainlist"><ul><li><span><a rel="mw:ExtLink nofollow" href="https://comptox.epa.gov/dashboard/chemical/details/DTXSID00193466" class="external text" target="_blank">DTXSID00193466</a> <span class="mw-valign-text-top noprint"><a href="/en/Q1927394#P3117" title="Edit this at Wikidata" class="image wl"><img loading="lazy" src="//upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/10px-OOjs_UI_icon_edit-ltr-progressive.svg.png" decoding="async" data-file-width="20" data-file-height="20" data-file-type="drawing" height="10" width="10" srcset="//upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/15px-OOjs_UI_icon_edit-ltr-progressive.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/8/8a/OOjs_UI_icon_edit-ltr-progressive.svg/20px-OOjs_UI_icon_edit-ltr-progressive.svg.png 2x" alt="OOjs_UI_icon_edit-ltr-progressive.svg"></a></span></span></li></ul></div></td></tr>

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<td colspan="2"><div class="collapsible-list mw-collapsible mw-collapsed" style="text-align: left;">
<div style="line-height: 1.6em; font-weight: bold; text-align:left; font-weight:normal; background:transparent;"><div><a href="/en/International_Chemical_Identifier" title="International Chemical Identifier" class="wl">InChI</a></div></div>
<ul class="mw-collapsible-content" style="margin-top: 0; margin-bottom: 0; line-height: inherit; list-style: none; margin-left: 0; word-break:break-all;"><li style="line-height: inherit; margin: 0"><div style="border-top:1px solid #ccc; padding:0.2em 0 0.2em 1.5em; text-align:left;"><div style="word-wrap:break-word; text-indent:-1.5em; font-size:97%; line-height:120%;">InChI=1S/C10H16/c1-6-7(2)9(4)10(5)8(6)3/h6H,1-5H3<sup><span>&nbsp;</span><span><span><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/7px-X_mark.svg.png" decoding="async" data-file-width="525" data-file-height="600" data-file-type="drawing" height="8" width="7" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/11px-X_mark.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/14px-X_mark.svg.png 2x" alt="X_mark.svg"></span></span><span style="display:none">N</span></sup></div><div style="word-wrap:break-word; text-indent:-1.5em; font-size:97%; line-height:120%;">Key:<span>&nbsp;</span>WQIQNKQYEUMPBM-UHFFFAOYSA-N<sup><span>&nbsp;</span><span><span><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/7px-X_mark.svg.png" decoding="async" data-file-width="525" data-file-height="600" data-file-type="drawing" height="8" width="7" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/11px-X_mark.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/14px-X_mark.svg.png 2x" alt="X_mark.svg"></span></span><span style="display:none">N</span></sup></div></div></li><li style="line-height: inherit; margin: 0"><div style="border-top:1px solid #ccc; padding:0.2em 0 0.2em 1.5em; text-align:left;"><div style="word-wrap:break-word; text-indent:-1.5em; font-size:97%; line-height:120%;">InChI=1/C10H16/c1-6-7(2)9(4)10(5)8(6)3/h6H,1-5H3</div><div style="word-wrap:break-word; text-indent:-1.5em; font-size:97%; line-height:120%;">Key:<span>&nbsp;</span>WQIQNKQYEUMPBM-UHFFFAOYAI</div></div></li></ul>
</div></td></tr>
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<td colspan="2"><div class="collapsible-list mw-collapsible mw-collapsed" style="text-align: left;">
<div style="line-height: 1.6em; font-weight: bold; text-align:left; font-weight:normal; background:transparent;"><div><a href="/en/Simplified_molecular-input_line-entry_system" title="Simplified molecular-input line-entry system" class="wl">SMILES</a></div></div>
<ul class="mw-collapsible-content" style="margin-top: 0; margin-bottom: 0; line-height: inherit; list-style: none; margin-left: 0; word-break:break-all;"><li style="line-height: inherit; margin: 0"><div style="border-top:1px solid #ccc; padding:0.2em 0 0.2em 1.6em; word-wrap:break-word; text-indent:-1.5em; text-align:left; font-size:97%; line-height:120%;">CC1=C(C)C(C)C(C)=C1C</div></li></ul>
</div></td></tr>

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<th colspan="2" style="background: #f8eaba; text-align: center;" class="notheme">Properties</th></tr>

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<td><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;"><a href="/en/Chemical_formula" title="Chemical formula" class="wl">Chemical formula</a></div></td>

<td>C<sub>10</sub>H<sub>16</sub><span> </span></td></tr>

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<td><a href="/en/Molar_mass" title="Molar mass" class="wl">Molar mass</a></td>

<td>136.24 g/mol<span> </span> <span> </span></td></tr>

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<td><a href="/en/Boiling_point" title="Boiling point" class="wl">Boiling point</a></td>
<td>55 to 60<span>&nbsp;</span>°C (131 to 140<span>&nbsp;</span>°F; 328 to 333<span>&nbsp;</span>K) at 13<span>&nbsp;</span>mmHg (1.7<span>&nbsp;</span>kPa)</td></tr>

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<td><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;"><a href="/en/Aqueous_solution" title="Aqueous solution" class="wl">Solubility in water</a></div></td>
<td>Sparingly soluble</td></tr>
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<th colspan="2" style="background: #f8eaba; text-align: center;" class="notheme">Hazards</th></tr>

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<td><a href="/en/Flash_point" title="Flash point" class="wl">Flash point</a></td>
<td>114<span>&nbsp;</span>°C (237<span>&nbsp;</span>°F; 387<span>&nbsp;</span>K)</td></tr>

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<td colspan="2" style="text-align:left; background:#f8eaba; border:1px solid #a2a9b1;" class="notheme"><div style="display: inline-block; line-height: 1.2em; padding: .1em 0;">Except where otherwise noted, data are given for materials in their <a href="/en/Standard_state" title="Standard state" class="wl">standard state</a> (at 25<span>&nbsp;</span>°C [77<span>&nbsp;</span>°F], 100<span>&nbsp;</span>kPa).</div>

<div style="margin-top: 0.3em;"><div style="text-align:center;"><span><span><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/12px-X_mark.svg.png" decoding="async" data-file-width="525" data-file-height="600" data-file-type="drawing" height="14" width="12" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/18px-X_mark.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/24px-X_mark.svg.png 2x" alt="X_mark.svg"></span></span><span style="display:none">N</span><span>&nbsp;</span><span class="reflink plainlinks nourlexpansion"><a rel="mw:ExtLink" href="//en.wikipedia.org/w/index.php?title=Special:ComparePages&amp;rev1=418038654&amp;page2=Pentamethylcyclopentadiene" class="external text" target="_blank">verify</a></span><span>&nbsp;</span>(<a href="/en/Wikipedia:WikiProject_Chemicals/Chembox_validation" title="Wikipedia:WikiProject Chemicals/Chembox validation" class="wl">what is</a><span>&nbsp;</span><sup><span><span><img loading="lazy" src="//upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/7px-Yes_check.svg.png" decoding="async" data-file-width="600" data-file-height="600" data-file-type="drawing" height="7" width="7" srcset="//upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/11px-Yes_check.svg.png 1.5x, //upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/14px-Yes_check.svg.png 2x" alt="Yes_check.svg"></span></span><span style="display:none">Y</span><span><span><img loading="lazy" src="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/7px-X_mark.svg.png" decoding="async" data-file-width="525" data-file-height="600" data-file-type="drawing" height="8" width="7" srcset="//upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/11px-X_mark.svg.png 1.5x, //upload.wikimedia.org/wikipedia/commons/thumb/a/a2/X_mark.svg/14px-X_mark.svg.png 2x" alt="X_mark.svg"></span></span><span style="display:none">N</span></sup><span>&nbsp;</span>?)

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<div style="margin-top: 0.3em; text-align: center;"><a href="/en/Wikipedia:Chemical_infobox#References" title="Wikipedia:Chemical infobox" class="wl">Infobox references</a></div></td></tr>



</tbody></table> <footer class='mobile-collapse-footer mobile-collapse-btn'><b>Close</b> <span class='arrow'>▲</span></footer></div><div class="shortdescription nomobile noexcerpt noprint searchaux" style="display:none" about="#mwt1">Chemical compound</div>



1,2,3,4,5-Pentamethylcyclopentadiene is a cyclic diene with the formula C5Me5H .  1,2,3,4,5-Pentamethylcyclopentadiene is the precursor to the ligand 1,2,3,4,5-pentamethylcyclopentadienyl, which is often denoted Cp* and read as "C P star", the "star" signifying the five methyl groups radiating from the core of the ligand. In contrast to less-substituted cyclopentadiene derivatives, Cp*H is not prone to dimerization. 