Cationic half-sandwich iron(II) and iron(III) complexes with N-heterocyclic carbene ligands

João M S Cardoso, Ana Fernandes, Bernardo De P Cardoso, Maria Deus Carvalho, Liliana P. Ferreira, Maria José Calhorda, Beatriz Royo Cantabrana

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23 Citations (Scopus)

Abstract

The cationic piano-stool iron complexes containing the N-heterocyclic carbene ligand tethered to a tetramethylcyclopentadienyl ring [(Cp∗-NHC)Fe(CO)(L)][X] (L = NCMe, DMSO; X = BF4, OTf) have been prepared and analyzed by spectroscopic, electrochemical, and crystallographic methods. Oxidation reactions of the cationic complex [(Cp∗-NHC)Fe(CO)(NCMe)][BF4] (2) with silver tetrafluoroborate and tert-butyl hydroperoxide in acetonitrile yield the dicationic iron(III) complexes [(Cp∗-NHC)Fe(NCMe)2][BF4]2 and [(Cp∗-NHC)Fe(H2O)][BF4]2, respectively. When the reaction of 2 with AgBF4 is performed in dichloromethane, the cationic complex [(Cp∗-NHC)FeCl][BF4] is obtained. These new iron(III) complexes have been characterized by Mössbauer spectroscopy and in one case by X-ray diffraction studies. DFT calculations were used to rationalize experimental results. The cationic complex [(Cp∗-NHC)Fe(CO)(NCMe)][OTf] is catalytically active toward the reduction of benzaldehyde and acetophenone using phenylsilane under neat conditions and in the absence of visible light irradiation.

Original languageEnglish
Pages (from-to)5670-5677
Number of pages8
JournalOrganometallics
Volume33
Issue number20
DOIs
Publication statusPublished - 27 Oct 2014

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