Unusual Coupling of Nitriles

  • Author: Hayley Charville
  • Published Date: 02 March 2014
  • Source / Publisher: Chemistry – A European Journal/Wiley-VCH
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
thumbnail image: Unusual Coupling of Nitriles

Related Societies

The formation and reactivity of small metallacycles, such as metallacyclopropenes, is well known; however, the formation of the analogous heterometallacycles, by the heterocoupling of a nitrile and an alkyne or the homocoupling of two nitriles, has received little attention.

Heinrich Lang, Technische Universität Chemnitz, Germany, and Uwe Rosenthal, Universität Rostock, Germany, and co-workers have discovered that the treatment of Group 4 (Ti and Zr) metallocene alkyne complexes with ferrocenyl-substituted nitriles Fc–C≡N and Fc–C≡C–C≡N results in nitrile–nitrile C–C homocoupling and nitrile–alkyne heterocoupling, respectively. Both reactions proved to be high yielding and highly selective. Indeed, for Fc–C≡N, the application of η5-pentamethylcyclopentadienyl (Cp*) ligands resulted in the coupling of the two nitriles by means of C–C bond formation, rather than by C–N or N–N bond formation, to give 1-metalla-2,5-diaza-cyclopenta-2,4-dienes. Interestingly, 3-ferrocenyl-2-propyne-nitrile (Fc–C≡C–C≡N) reacted differently, resulting in nitrile–alkyne C–C coupling of the two nitriles and the synthesis of 1-metalla-2-aza-cyclopenta-2,4-dienes.



Electrochemical measurements were also carried out by using cyclic voltammetry and these show irreversible oxidations, which initiate decomposition, for all of the heterometallacycles synthesized. For the 1-metalla-2,5-diaza-cyclopenta-2,4-dienes the influence of the ferrocenyl substituent is particularly interesting. The ferrocenyl–zirconium compound was found to be more stable against oxidation than the analogous tolyl–zirconium compound, whereas for the titanium complexes the stability was reversed. For the 1-metalla-2-aza-cyclopenta-2,4-dienes, redox-active products and several redox processes were observed. Owing to the different potentials of the reaction intermediates, different decomposition mechanisms have been predicted.


Article Views: 3945

Sign in Area

Please sign in below

Additional Sign In options

Please note that to comment on an article you must be registered and logged in.
Registration is for free, you may already be registered to receive, e.g., the newsletter. When you register on this website, please ensure you view our terms and conditions. All comments are subject to moderation.

Article Comments - To add a comment please sign in

If you would like to reuse any content, in print or online, from ChemistryViews.org, please contact us first for permission. more

Follow on Facebook Follow on Twitter Follow on LinkedIn Follow on Instagram RSS Sign up for newsletters

Magazine of Chemistry Europe (16 European Chemical Societies) published by Wiley-VCH