Difference between revisions 6001544 and 6001545 on simplewiki

{{Chembox new
| ImageFileL1 = Ferrocene-2D.png
| ImageSizeL1 = 80 px
| ImageFileR1 = Ferrocene-3D-balls-B.png
| ImageSizeR1 = 120 px
| IUPACName = ferrocene, bis(η<sup>5</sup>-cyclopentadienyl)iron
| OtherNames = ferrocene, iron cyclopentadienyl 
| Section1 = {{Chembox Identifiers
(contracted; show full)
 | author = T. J. Kealy, P. L. Pauson
 | title = A New Type of Organo-Iron Compound
 | journal = Nature
 | year = 1951 
 | volume = 168 
 | pages = 1039
 | doi = 10.1038/1681039b0}}</ref> This stability was accorded to the aromatic character of the negative charged cyclopentadienyls, but the sandwich structure of the η<sup>5</sup> (pentahapto) compound was not recognized by them.
  

[[Robert Burns Woodward]] and [[Geoffrey Wilkinson]] deduced the structure based on its reactivity.<ref>{{cite journal
 | author = G. Wilkinson, M. Rosenblum, M. C. Whiting, R. B. Woodward
 | title = The Structure of Iron Bis-Cyclopentadienyl
 | journal = [[Journal of the American Chemical Society]]
 | year = 1952
 | volume = 74
(contracted; show full)]]. Each cyclopentadienyl (Cp) ring is then allocated a single negative charge, bringing the number of π-electrons on each ring to six, and thus making them [[aromaticity|aromatic]].  These twelve electrons (six from each ring) are then shared with the metal ''via'' covalent bonding, which, when combined with the six ''d''-electrons on Fe<sup>2+</sup>, results in the complex having an [[18-electron rule|18-electron]], [[noble gas]] electron configuration.
    

The lack of individual bonds between the carbon atoms of the Cp ring and the Fe<sup>2+</sup> ion results in the Cp rings to freely rotate about the Cp<sub>(centroid)</sub>-Fe-Cp<sub>(centroid)</sub> axis, as observed by [[Nuclear Magnetic Resonance]]<ref>{{cite journal
 | author = E. W. Abel, N. J. Long, K. G. Orrell, A. G. Osborne, V. Sik
 | title = Dynamic NMR studies of ring rotation in substituted ferrocenes and ruthenocenes
(contracted; show full)

Ferrocenium salts are sometimes used as oxidizing agents, in part because the product ferrocene is fairly inert and readily separated from ionic products.<ref>{{cite journal|author=N. G. Connelly, W. E. Geiger| title=Chemical Redox Agents for Organometallic Chemistry|journal=[[Chemical Reviews]]|
dateyear= 1996| volume= 96| pages= 877–910| doi=10.1021/cr940053x}}</ref>  Substituents on the cyclopentadienyl ligands alters the redox potential in the expected way: electron withdrawing group such as a carboxylic acid shift the potential in the [[anodic]] direction (''i.e.'' made more positive), whereas electron releasing groups such as [[methyl]] groups shift the potential in the [[cathodic]] direction (more negative). Thus, decamethylferrocene is much more easy to oxidise than ferroce(contracted; show full)

In [[diesel]]-fuelled engines, ferrocene reduces the production of soot.

===Pharmaceutical===
Some ferrocenium salts exhibit anticancer activity, and an experimental drug has been reported which is a ferrocenyl version of [[tamoxifen]].<ref name = top2003 /> The idea is that the tamoxifen will bind to the [[estrogen]] binding sites, resulting in a cytotoxicity effect.<ref>{{cite journal|journal=[[Chemical and Engineering News]] | date=16 Sep
tember 2002| title= The Bio Side of Organometallics | author= Ron Dagani| volume = 80| issue= 37| pages = 23–29| url=http://pubs.acs.org/cen/science/8037/8037sci1.html}}</ref><ref>
{{cite journal|author=S. Top, B. Dauer, J. Vaissermann and G. Jaouen| journal=[[Journal of Organometallic Chemistry]]| title= Facile route to ferrocifen, 1-[4-(2-dimethylaminoethoxy)]-1-(phenyl-2-ferrocenyl-but-1-ene), first organometallic analogue of tamoxifen, by the McMurry reaction | doi=10.1016/S0022-328X(97)00086-7 |dateyear=1997| volume=541| pages= 355–361}}</ref><ref name=top2003>{{cite journal|author=S. Top, A. Vessières, G. Leclercq, J. Quivy, J. Tang, J. Vaissermann, M. Huché and G. Jaouen| title=Synthesis, Biochemical Properties and Molecular Modelling Studies of Organometallic Specific Estrogen Receptor Modulators (SERMs), the Ferrocifens and Hydroxyferrocifens: Evidence for an Antiproliferative Effect of Hydroxyferrocifens on both Hormone-Dependent and Hormone-Independent Breast Cancer Cell Lines| journal=Chemistry, a European Journal| dateyear=2003| volume=9| pages=5223–36 | pmid=14613131 | doi=10.1002/chem.200305024}}</ref>

===Materials chemistry===
Ferrocene, being readily sublimed, can be used to deposit certain kinds of fullerenes, especially carbon nanotubes. Due to the fact that many organic reactions can be used to modify ferrocenes, it is the case that [[vinyl]] ferrocene can be made. The vinyl ferrocene can be made by a [[Wittig reaction]] of the [[aldehyde]], a [[phosphonium salt]] and [[sodium hydroxide]].<ref>Liu, Wan-yi(contracted; show full)

Because of the ease of substitution, many structurally unusual ferrocene derivatives have been prepared. For example, the penta(ferrocenyl)cyclopentadienyl ligand <ref>{{cite journal|author=Y. Yu, A.D. Bond, P. W. Leonard, K. P. C. Vollhardt, G. D. Whitener| title=Syntheses, Structures, and Reactivity of Radial Oligocyclopentadienyl Metal Complexes: Penta(ferrocenyl)cyclopentadienyl and Congeners| journal= [[Angewandte Chemie International Edition]]| volume =45 | issue=11| pages= 1794–1799|
dateyear=2006| doi=10.1002/anie.200504047}}</ref>, features a cyclopentadiene derivatised with five ferrocene substituents.

[[Image:Penta(ferrocenyl)cyclopentadienyl.png|500px|center|Penta(ferrocenyl)cyclopentadienyl ligand]]

[[Image:Hexaferrocenylbenzene-3D-sticks.png|200px|thumb|right|Structure of hexaferrocenylbenzene]]

In '''hexaferrocenylbenzene''', all six positions on a [[benzene]] molecule have ferrocenyl substituents ('''R''') <ref>{{cite journal|title=Hexaferrocenylbenzene|author= Yong Yu, Andrew D. Bond, Philip W. Leonard, Ulrich J. Lorenz, Tatiana V. Timofeeva, K. Peter C. Vollhardt, Glenn D. Whitener and Andrey A. Yakovenko| journal=[[Chemical Communications]]| dateyear=2006| pages= 2572–2574 |doi=10.1039/b604844g}}</ref>. [[X-ray diffraction]] analysis of this compound confirms that the cyclopentadienyl ligands are not co-planar with the benzene core but have alternating [[dihedral angle]]s of +30° and −80°. Due to steric crowding the ferrocenyls are slightly bent with angles of 177° and have elongated C-Fe bonds. The quaternary cyclopentadienyl carbon atoms are also [[pyramidalization|pyramidalized]]. <ref>Also, the benzene core has a [[chair conformation]] with dihedral angles of 14° and displays [[bond length]] alternation between 142.7 [[picometer|pm]] and 141.1 pm, both indications of steric crowding of the substituents.</ref>

<br clear = all/>

==References==
{{reflist|2}}

{{commonscat|ferrocene}}

==Further reading==
;Announcement of the discovery of ferrocene, but with wrong structure
*{{cite journal|author=Kealy, T. J., Pauson, P. L.|title=A New Type of Organo-iron Compound|journal= [[Nature (journal)|Nature]]| dateyear= 1951 | volume= 168| pages =1039–40 | doi = 10.1038/1681039b0}}
* {{cite journal| author=Miller, S. A., Tebboth, J. A., Tremaine, J. F.|journal= [[Journal of the Chemical Society]] | dateyear=1952| pages= 632–635| title=114. Dicyclopentadienyliron |doi=10.1039/JR9520000632}}
;Announcement of the correct 'sandwich' structure
*{{cite journal|author=[[Geoffrey Wilkinson|Wilkinson, G.]], Rosenblum, M., Whiting, M. C., [[Robert Burns Woodward|Woodward, R. B.]]|title= The Structure of Iron Bis-Cyclopentadienyl| journal=[[Journal of the American Chemical Society]]|dateyear= 1952| volume=74|pages=2125–2126 | doi = 10.1021/ja01128a527}}
*{{cite journal |author=Fischer, E. O., Pfab, W.|title=Cyclopentadien-Metallkomplexe, ein neuer typ metallorganischer Verbindungen |journal=[[Zeitschrift für Naturforschung B]]|dateyear=1952| volume=7 |pages=377–379}}
;Others
*{{cite journal|author=Dunitz, J. D., Orgel, L. E.|title=Bis-Cyclopentadienyl - A Molecular Sandwich|journal= [[Nature (journal)|Nature]] |dateyear=1953| volume=171 |pages= 121–122 | doi = 10.1038/171121a0}}
*{{cite journal|author=Pauson, P. L.|title=Ferrocene-how it all began|journal=[[Journal of Organometallic Chemistry]]|dateyear=2001|pages=637–639 | volume = 637-639 | doi = 10.1016/S0022-328X(01)01126-3}}
*{{cite book|author= Gerard Jaouen (ed.)| title=Bioorganometallics: Biomolecules, Labeling, Medicine| publisher=Wiley-VCH| location= Weinheim| year= 2006 | isbn=978-3-527-30990-0}} (discussion of biological role of ferrocene and related compounds)

[[Category:Iron compounds]]
[[Category:Metallocenes]]
[[Category:Antiknock agents]]

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