查看“︁六重键”︁的源代码

{{noteTA|G1=Chemistry}}
[[File:MolybdenumMOdiagram.png|thumb|right|400px|<chem>Mo2</chem>的[[分子轨道]]示意图]]

'''六重键（'''{{Lang-en|Sextuple Bond}}'''），'''是指化學中，由6對[[價電子]]組成的[[共价键]]。

六重键的[[键级]]為6，含有六重鍵的[[化合物]]仅有[[双原子分子]]的<chem>Mo2</chem>和<chem>W2</chem>，而它们仅在非常低的温度下存在于[[氣相|气相]]。

尽管双原子的<chem>Cr2</chem>和<chem>U2</chem>也有名义上的6對[[價電子]]組成的键，但根据[[量子化学]]的计算，它们的有效[[键级]]小于5，可能是[[五重键]]。<ref>{{Cite journal|title=Reaching the Maximum Multiplicity of the Covalent Chemical Bond|url=http://onlinelibrary.wiley.com/doi/10.1002/ange.200603600/abstract|last=Roos|first=Björn O.|last2=Borin|first2=Antonio C.|date=2007-02-19|journal=Angewandte Chemie|issue=9|doi=10.1002/ange.200603600|volume=119|pages=1491–1494|language=en|issn=1521-3757|last3=Gagliardi|first3=Laura|access-date=2018-01-30|archive-date=2018-01-30|archive-url=https://web.archive.org/web/20180130205904/http://onlinelibrary.wiley.com/doi/10.1002/ange.200603600/abstract|dead-url=no}}</ref>

有很强的证据显示，元素周期表中任何两个元素之间不可能形成键级超过六的化学键<ref>{{cite journal | last = Roos | first = Björn O. | coauthors = Antonio C. Borin, and Laura Gagliardi | year = 2007 | title = Reaching the Maximum Multiplicity of the Covalent Chemical Bond | journal = [[Angewandte Chemie International Edition]] | doi = 10.1002/anie.200603600 }}</ref>。

气相中的<chem>Mo2</chem>的观测必须在很低的温度（7[[开尔文|K]]），使用[[激光蒸发技术]]，用[[近红外光谱]]或[[紫外光谱]]进行观测。<ref>{{cite journal | title = On the dimers of the VIB group: a new NIR electronic state of Mo<sub>2</sub> | author = D. Kraus, M. Lorenz and V. E. Bondybey | journal = [[PhysChemComm]] | year = 2001 | volume = 4 | pages = 44 - 48 | doi = 10.1039/b104063b}}</ref> 

科學界期望可以於<chem>Mo2</chem>發現到與<chem>Cr2</chem>觀察結果類似的一對[[双自由基]]<ref>{{cite journal | title = The Many Ways To Have a Quintuple Bond | author = Gabriel Merino, Kelling J. Donald, Jason S. D’Acchioli, and Roald Hoffmann | journal = [[J. Am. Chem. Soc.]] | year = 2007 | volume = 129 | issue = 49 | pages = 15295 -15302 | doi = 10.1021/ja075454b}}</ref>。 

更高的键级将会反映在更短的键长上，仅有1.94 [[埃格斯特朗 (单位)|Å]]。{{Fact}}

== 参见 ==
*[[钼|鉬]]（<chem>Mo</chem>）
*[[钨|鎢]]（<chem>W</chem>）
*[[铬|鉻]]（<chem>Cr</chem>）
*[[鈾]]（<chem>U</chem>）
*[[價電子]]

== 参考文献 ==
{{reflist}}

== 扩展阅读 ==
{{refbegin|2}}
*{{cite journal|doi=10.1021/ja00540a034|title=Dimolybdenum: nature of the sextuple bond|year=1980|author=Bruce E. Bursten; F. Albert Cotton; Michael B. Hall|journal=Journal of the American Chemical Society|volume=102|pages=6348|issue=20}}
*{{cite journal|doi=10.1016/j.chemphys.2007.05.028|title=A theoretical study of the binding and electronic spectrum of the Mo2 molecule|year=2008|author=Borin, A|journal=Chemical Physics|volume=343|pages=210|last2=Gobbo|first2=João Paulo|last3=Roos|first3=Björn O.|issue=2–3}}
*{{cite journal|doi=10.1021/j150603a001|title=The "sextuple" bond of chromium dimer|year=1981|author=Marvin M. Goodgame; William A. Goddard I I I|journal=The Journal of Physical Chemistry|volume=85|pages=215|issue=3}}
*{{cite journal|doi=10.1073/pnas.0610364104|author=Chisholm, Mh|title=Metal to metal multiple bonds in ordered assemblies|volume=104|issue=8|pages=2563–70|pmid=17299047|pmc=1815223|journal=Proceedings of the National Academy of Sciences of the United States of America|url=http://www.pnas.org/cgi/pmidlookup?view=long&pmid=17299047|format=Free full text|date=Feb 2007|access-date=2012-08-12|archive-date=2020-01-24|archive-url=https://web.archive.org/web/20200124224424/http://www.pnas.org/cgi/pmidlookup?view=long&pmid=17299047|dead-url=no}}
*{{cite journal|title=Metal-metal bond energies in diatomic molybdenum, octachloromolybdate (Mo2Cl84-), and molybdenum formate (Mo2(O2CH)4)|url=https://archive.org/details/sim_journal-of-computational-chemistry_1980_spring_1_1/page/59|author=Norman, Joe G., Jr.; Ryan, P. Barry|journal=Journal of Computational Chemistry|year=1980|volume=1|issue=1|pages=59–63|doi=10.1002/jcc.540010107}}
*{{cite journal|title=Electron correlation and the nature of the sextuple bond in the dimolybdenum molecule|author= Atha, P. M.; Hillier, I. H.; Guest, M. F.|journal=Chemical Physics Letters|year=1980|volume=75|issue=1|pages=84–86|doi=10.1016/0009-2614(80)80469-6}}
*{{cite journal|title=Theoretical study of the electronic structure of the transition metal dimers, discandium, dichromium, dimolybdenum, and dinickel|author=Wood, Carol; Doran, Mark; Hillier, Ian H.; Guest, Martyn F.|journal=Faraday Symp. R. Soc. Chem.|year=1980|volume=14|issue=Diatomic Met. Met. Clusters|pages=159–169|doi=10.1039/fs9801400159}}
{{refend}}

{{Diatomicelements}}
{{化学键}}
{{Chemical bonding theory|state=autocollapse}}

[[Category:化学键]]
[[Category:共價鍵]]