Difference between revisions 6001812 and 6001813 on simplewiki

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==Structure and bonding==
The carbon–carbon bond distances are 1.40 Å within the five-membered rings, and the Fe–C bond distances are 2.04 Å.  
Although [[X-ray crystallography]] (in the monoclinic space group) points to the Cp rings being in a staggered conformation, i due to imposed molecular centrosymmetric symmetry in the space group.<ref>{{Cite journal|last=Eiland|first=Philip Frank|last2=Pepinsky|first2=Ray|date=1952-10-01|title=X-RAY EXAMINATION OF IRON BISCYCLOPENTADIENYL|url=http://dx.doi.org/10.1021/ja01139a527|journal=Journal of the American Chemical Society|volume=74|issue=19|pages=4971–4971|doi=10.1021/ja01139a527|issn=0002-7863}}</ref> Below 110 K, ferrocene crystallizes in an orthorhombic crystal lattice in which the Cp rings are ordered and eclipsed.<ref>{{Cite journal|last=Seiler|first=P.|last2=Dunitz|first2=J. D.|date=1982-06-15|title=Low-temperature crystallization of orthorhombic ferrocene: structure analysis at 98 K|url=http://scripts.iucr.org/cgi-bin/paper?S0567740882007080|journal=Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry|language=en|volume=38|issue=6|pages=1741–1745|doi=10.1107/s0567740882007080|issn=0567-7408}}</ref> It has been shown through gas phase electron diffraction<ref>{{cite journal | last1 = Haaland | first1 = A. | last2 = Nilsson | first2 = J. E. | year = 1968 | title = The Determination of Barriers to Internal Rotation by Means of Electron Diffraction. Ferrocene and Ruthenocene | url = | journal = [[Acta Chemica Scandinavica|Acta Chem. Scand.]] | volume = 22 | issue = | pages = 2653–2670 | doi = 10.3891/acta.chem.scand.22-2653 }}</ref> and computational studies<ref>{{cite journal | last1 = Coriani | first1 = Sonia | last2 = Haaland | first2 = Arne | last3 = Helgaker | first3 = Trygve | last4 = Jørgensen | first4 = Poul | year = 2006 | title = The Equilibrium Structure of Ferrocene | url = | journal = [[ChemPhysChem]] | volume = 7 | issue = | pages = 245–249 | doi = 10.1002/cphc.200500339 }}</ref> that in the gas phase the Cp rings are eclipsed. The staggered conformation is believed to be most stable in the condensed phase due to crystal packing. The point group of the staggered conformation is D<sub>5d</sub> and the point group of the eclipsed conformation is D<sub>5h</sub>.  

The Cp rings rotate with a low barrier about the Cp<sub>(centroid)</sub>–Fe–Cp<sub>(centroid)</sub> axis, as observed by measurements on substituted derivatives of ferrocene using <sup>1</sup>H and <sup>13</sup>C [[nuclear magnetic resonance]] spectroscopy.  For example, methylferrocene (CH<sub>3</sub>C<sub>5</sub>H<sub>4</sub>FeC<sub>5</sub>H<sub>5</sub>) exhibits a singlet for the C<sub>5<(contracted; show full){{commons category|ferrocene}}

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[[Category:Antiknock agents]]
[[Category:Sandwich compounds]]
[[Category:Cyclopentadienyl complexes]]
[[Category:Ferrocenes]]