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Organorhenium chemistry
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<h2 id="general-features">General features</h2> <p>Rhenium exists in ten known oxidation states from −3 to +7 except −2, and all but Re(−3) are represented by organorhenium compounds. Most are prepared from salts of <a href="/facts/Perrhenate/uKvDsaoY">perrhenate</a> and related binary oxides.<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> The halides, e.g., <a href="/facts/Rhenium_pentachloride/K989aTxt">ReCl5</a> are also useful precursors as are certain oxychlorides. </p><p>A noteworthy feature of organorhenium chemistry is the coexistence of oxide and organic ligands in the same <a href="/facts/Coordination_sphere/s3vUKWjp">coordination sphere</a>.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> </p> <h2 id="carbonyl-compounds">Carbonyl compounds</h2> <p><a href="/facts/Dirhenium_decacarbonyl/65J7DvAv">Dirhenium decacarbonyl</a> is a common entry point to other rhenium carbonyls. The general patterns are similar to the related <a href="/facts/Manganese_carbonyl/rwP8qEBU">manganese carbonyls</a>. It is possible to reduce this dimer with sodium <a href="/facts/Amalgam_(chemistry)/5dRXJyt3">amalgam</a> to Na[Re(CO)5] with rhenium in the formal oxidation state −1. Bromination of dirhenium decacarbonyl gives <a href="/facts/Bromopentacarbonylrhenium(I)/NsNzY2uj">bromopentacarbonylrhenium(I)</a>,<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> then reduced with <a href="/facts/Zinc/80b1qgk3">zinc</a> and <a href="/facts/Acetic_acid/uyBKA2Pd">acetic acid</a> to <a href="/facts/Pentacarbonylhydridorhenium/IPt1GquY">pentacarbonylhydridorhenium</a>:<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p> Re2(CO)10 + Br2 → 2 Re(CO)5Br Re(CO)5Br + Zn + HOAc → Re(CO)5H + ZnBr(OAc) <p>Bromopentacarbonylrhenium(I) is readily decarbonylated. In refluxing water, it forms the triaquo cation:<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> </p> Re(CO)5Br + 3 H2O → [Re(CO)3(H2O)3]Br + 2 CO <p>With <a href="/facts/Tetraethylammonium_bromide/WNaoSEEc">tetraethylammonium bromide</a> Re(CO)5Br reacts to give the anionic tribromide:<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p> Re(CO)5Br + 2 NEt4Br → [NEt4]2[Re(CO)3Br3] + 2 CO <h2 id="cyclopentadienyl-complexes">Cyclopentadienyl complexes</h2> <p>One of the first <a href="/facts/Transition_metal_hydride/LKwz9A8M">transition metal hydride</a> complexes to be reported was (C5H5)2ReH. A variety of <a href="/facts/Half-sandwich_compound/vu6MyRNq">half-sandwich compounds</a> have been prepared from (C5H5)Re(CO)3 and (C5Me5)Re(CO)3. Notable derivatives include the electron-precise oxide (C5Me5)ReO3 and (C5H5)2Re2(CO)4. </p> <h2 id="re-alkyl-and-aryl-compounds">Re-alkyl and aryl compounds</h2> <p>Rhenium forms a variety of alkyl and aryl derivatives, often with pi-donor coligands such as oxo groups. Well known is <a href="/facts/Methylrhenium_trioxide/mphJb8Rf">methylrhenium trioxide</a> ("MTO"), CH3ReO3 a volatile, colourless solid, a rare example of a stable high-oxidation state metal alkyl complex. This compound has been used as a <a href="/facts/Catalyst/LPBS7TQC">catalyst</a> in some laboratory experiments. It can be prepared by many routes, a typical method is the reaction of Re2O7 and <a href="/facts/Tetramethyltin/NcUW8FHb">tetramethyltin</a>:<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p> Re2O7 + (CH3)4Sn → CH3ReO3 + (CH3)3SnOReO3 <p>Analogous alkyl and aryl derivatives are known. Although PhReO3 is unstable and decomposes at –30 °C, the corresponding sterically hindered mesityl and 2,6-xylyl derivatives (MesReO3 and 2,6-(CH3)2C6H3ReO3) are stable at room temperature. The electron poor 4-trifluoromethylphenylrhenium trioxide (4-CF3C6H4ReO3) is likewise relatively stable.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a> MTO and other organylrhenium trioxides catalyze oxidation reactions with <a href="/facts/Hydrogen_peroxide/vju6HBIc">hydrogen peroxide</a> as well as olefin metathesis in the presence of a Lewis acid activator.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> Terminal <a href="/facts/Alkyne/VHI4N5Wo">alkynes</a> yield the corresponding acid or ester, internal alkynes yield diketones, and <a href="/facts/Alkene/RtYcS6kU">alkenes</a> give epoxides. MTO also catalyses the conversion of <a href="/facts/Aldehyde/xSIRkW03">aldehydes</a> and <a href="/facts/Diazoalkane/qNcCkYb8">diazoalkanes</a> into an alkene.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> </p><p>Rhenium is also able to make complexes with <a href="/facts/Fullerene_Ligands/X5872BB8">fullerene ligands</a> such as Re2(PMe3)4H8(η2:η2C60). </p> <h2 id="further-reading">Further reading</h2> <ul><li><i>Synthesis of Organometallic Compounds: A Practical Guide</i> Sanshiro Komiya Ed. S. Komiya, M. Hurano 1997.</li> <li>Pericles Stavropoulos, Peter G. Edwards, Geoffrey Wilkinson, Majid Motevalli, K. M. Abdul Malik and Michael B. Hursthouse "Oxoalkyls of rhenium-(V) and-(VI). X-Ray crystal structures of (Me4ReO)2Mg(thf)4,[(Me3SiCH2)4ReO]2Mg(thf)2, Re2O3Me6 and Re2O3(CH2SiMe3)6" J. Chem. Soc., Dalton Trans., 1985, pp. 2167-2175. <a href="/facts/Doi_(identifier)/muM9Etpq">doi</a>:<a href="https://doi.org/10.1039%2FDT9850002167">10.1039/DT9850002167</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>O. Glemser "Ammonium Perrhenate" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1476-85. <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>W. A. Herrmann and F. E. Kuhn (1997). "Organorhenium Oxides". Acc. Chem. Res. 30 (4): 169–180. doi:10.1021/ar9601398. <a href="/wiki/Acc._Chem._Res." target="_blank">/wiki/Acc._Chem._Res.</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Schmidt, Steven P.; Trogler, William C.; Basolo, Fred (1990). Pentacarbonylrhenium Halides. Inorganic Syntheses. Vol. 28. pp. 154–159. doi:10.1002/9780470132593.ch42. ISBN 978-0-470-13259-3. <a href="978-0-470-13259-3" target="_blank">978-0-470-13259-3</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Michael A. Urbancic, John R. Shapley (1990). "Pentacarbonylhydridorhenium". Inorganic Syntheses. Vol. 28. pp. 165–168. doi:10.1002/9780470132593.ch43. ISBN 978-0-470-13259-3. <a href="978-0-470-13259-3" target="_blank">978-0-470-13259-3</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Lazarova, N.; James, S.; Babich, J.; Zubieta, J. (2004). "A convenient synthesis, chemical characterization and reactivity of [Re(CO)3(H2O)3]Br: the crystal and molecular structure of [Re(CO)3(CH3CN)2Br]". Inorganic Chemistry Communications. 7 (9): 1023–1026. doi:10.1016/j.inoche.2004.07.006. <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>Alberto, R.; Egli, A.; Abram, U.; Hegetschweiler, K.; Gramlich V.; Schubiger, P. A. (1994). "Synthesis and reactivity of [NEt4]2[ReBr3(CO)3]. Formation and structural characterization of the clusters [NEt4][Re3(µ3-OH)(µ-OH)3(CO)9] and [NEt4][Re2(µ-OH)3(CO)6] by alkaline titration". J. Chem. Soc., Dalton Trans. (19): 2815–2820. doi:10.1039/DT9940002815. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Romão, Carlos C.; Kühn, Fritz E.; Herrmann, Wolfgang A. (1997). "Rhenium(VII) Oxo and Imido Complexes: Synthesis, Structures, and Applications". Chemical Reviews. 97 (8): 3197–3246. doi:10.1021/cr9703212. PMID 11851489. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Dyckhoff, Florian; Li, Su; Reich, Robert M.; Hofmann, Benjamin J.; Herdtweck, Eberhardt; Kühn, Fritz E. (2018). "Synthesis, characterization and application of organorhenium(vii) trioxides in metathesis reactions and epoxidation catalysis". Dalton Transactions. 47 (29): 9755–9764. doi:10.1039/c8dt02326c. ISSN 1477-9226. PMID 29987275. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Schmidt, Boris (1997). "Methyltrioxorhenium - from oxidation and cyclopropanation to metathesis". Journal für Praktische Chemie/Chemiker-Zeitung. 339 (1): 493–496. doi:10.1002/prac.19973390190. ISSN 0941-1216. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>Hudson, A. "Methyltrioxorhenium" Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons: New York, 2002. <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> </ol>