Dinuclear Hafnocene(IV) Complexes

  • Author: Sarah Maier
  • Published: 14 September 2021
  • Copyright: Wiley-VCH GmbH
  • Associated Societies: American Chemical Society (ACS), USA
thumbnail image: Dinuclear Hafnocene(IV) Complexes

Hafnium is the heaviest stable group 4 transition metal. Complexes of the lighter group 4 elements titanium and zirconium have applications, e.g., in catalysis. The use of hafnium compounds is much less common even though hafnium compounds can be useful for bond-activation reactions. Titanium and zirconium are well known for the formation of titanocene and zirconocene complexes, but only relatively few corresponding hafnocene complexes have been described so far.


Fabian Reiß, Torsten Beweries, Leibniz Institute for Catalysis, Rostock, Germany, and colleagues have synthesized two dinuclear, allenediide-bridged hafnocene(IV) complexes. Cp2HfCl2 and the dilithioallene precursor Li2(Me3SiC3SiMe3) were reacted in toluene at –78 °C under a nitrogen atmosphere. The products were characterized using NMR spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction. Depending on the stoichiometry, two different complexes were formed. Two equivalents of the hafnium compound and one equivalent of the allenediide precursor gave a complex containing one bridging allenediide group and two chloride ligands. Equimolar amounts of both precursors led to a product with two bridging allenediide ligands (pictured).


The properties of the two complexes differ considerably. The mono-allenediide complex is air- and moisture-sensitive and was isolated in a yield of 21 %. The complex with two alllenediide bridges was isolated in a yield of 90 %. It is stable in air and various solvents, including water. The researchers attribute this high stability to the shielding effects of the cyclopentadienyl and trimethylsilyl units surrounding the metal center.


 

 

Article Views: 694

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 and consult our permission guidance prior to making your request

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

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