Iron and Cobalt Metallotropism in Remote‐Substituted NHC Ligands: Metalation to Abnormal NHC Complexes or NHC Ring Opening. Issue 44 (19th September 2018)

• Record Type: Journal Article
• Authors: Danopoulos, Andreas A.; Massard, Alexandre; Frison, Gilles; Braunstein, Pierre
• Is Part Of: Angewandte Chemie international edition. Volume 57:Issue 44(2018)
• Page Start: 14550
• Page End: 14554
• Publication Date: 2018-09-19
• Subjects: cobalt -- dinuclear complex -- iron -- metallotropism -- N-heterocyclic carbenes; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201808008
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Metallotropism of the M[N(SiMe3 )2 ]2 metal fragment in the tautomeric systemIA R ⇌AC R involving imidazolium salts/N‐heterocyclic carbenes with remote aminide/amine substituents, respectively, is manifested by its CNHC carbophilicity (R=tBu, M=Co, Fe) or NRaminido nitrogenophilicity (R=Cy, M=Co, Fe; R=Mes, M=Fe) and has been rationalized on the basis of steric and electronic effects. The thermolysis products of the [M{N(SiMe3 )2 }2 ]/IA R ⇌AC R system are also substituent‐dependent, leading to a rearranged aminide‐functionalized aNHC Co2 complex of an unprecedented type or to ring‐opened metallaketenimines; they are postulated to originate from different metalloisomers. The results are interpreted on the basis of the X‐ray diffraction analysis of 11 new compounds. Abstract : Metallotropism in tautomers arises from stereoelectronic fine‐tuning of (Fe or Co){N(SiMe3 )2 }2 bonding to CNHC or remote N in NHCs/imidazolium salts with amine/aminide substituents, respectively. Thermally induced unexpected formation of a Co I −Co II dinuclear complex and NHC ring opening leading to metallaketenimines were observed.