Ferrocenophanes

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General structure of the ferrocenophanes (ER m e.g. C 2 H 4 , SnR 2 , SiR 2 or PPh).

Ferrocenophane , also ansa-ferrocene ( ansa (Greek): handle, handle), are organometallic compounds that are derived from ferrocene . In this class of compounds, the cyclopentadienyl ligands of ferrocene are linked by one or more bridging groups. This hinders the rotation of the cyclopentadienyl ligands with respect to one another and changes the reactivity of the complex with respect to the parent compound ferrocene. A variety of organic and inorganic groups are suitable as bridging groups.

nomenclature

1,2,3-trithio [3] ferrocenophane

In ferrocenophanes, the number of bridging atoms is indicated by a number in square brackets in front of the name. [2] Ferrocenophanes are, for example, ferrocenophanes with two bridging atoms. Ferrocenophanes with several atoms in a bridge get correspondingly higher numbers. In the case of multiple bridged ferrocenophanes, the number of bridging atoms is shown in several brackets, for example a ferrocenophane with two bridges each containing three atoms is referred to as [3] [3] ferrocenophane.

history

The first representatives of this class of compounds were produced in the 1950s.

properties

Conformations of ferrocene . Left: staggered; right: ecliptic.

An important parameter is the angle that the two cyclopentadienyl ligands adopt with respect to one another. The reactivity often increases with increasing angle. Carbon-bridged [1] ferrocenophanes do not exist due to the high ring strain . For heteroatom-bridged [1] ferrocenophanes, bond angles of 18 to 27 ° are known. Depending on the bridging, the cyclopentadienyl ligands of the ferrocene base can have a staggered or ecliptic conformation .

Depending on the type of bridging, the ferrocenophanes can have various elements of symmetry , such as a twofold axis of symmetry. There are ferrocenophanes which are optically active due to their configuration . Because of their rigid conformation, some of the optically active ferrocenophane derivatives can be separated into their enantiomers, for example by resolution .

Manufacturing

Production of ferrocenophanes via dilithium ferrocene.

An important starting compound for the production of ferrocenophanes is dilithium ferrocene . This can be produced simply by reacting ferrocene with n -butyllithium in the presence of tetramethylethylenediamine . By reacting dilithium ferrocene with, for example, dimethyldichlorosilane , silicon-bridged ferrocenophanes can be produced.

application

Ferrocenophanes are used in the production of polyferrocenes by ring-opening polymerization .

Web links

Commons : Ferrocenophane  - Collection of images, videos and audio files
Wiktionary: Ferrocenophane  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. ^ A b c Rolf Gleiter, Henning Hopf: Modern Cyclophane Chemistry , Wiley-VCH, 2004, ISBN 978-3-527-30713-5 , pp. 131–154.
  2. ↑ A. Lüttringhaus, W. Kullick: Ansa-ferrocene. In: Angewandte Chemie. 70, 1958, p. 438, doi : 10.1002 / ange.19580701407 .
  3. ↑ Andrew J. Locke, Christopher J. Richards, David E. Hibbs, Michael B. Hursthouse: Synthesis and X-ray crystal structure analysis of a scalemic C2-symmetric ferrocenophane. In: Tetrahedron: Asymmetry. 8, 1997, p. 3383, doi : 10.1016 / S0957-4166 (97) 00466-7 .
  4. ^ Harry R. Allcock: Inorganic-Organic Polymers. In: Advanced Materials. 6, 1994, p. 106, doi : 10.1002 / adma.19940060203 .