Cationic Nickel d9‐Metalloradicals [Ni(NHC)2]+. Issue 31 (22nd September 2022)

• Record Type: Journal Article
• Authors: Tendera, Lukas; Luff, Martin S.; Krummenacher, Ivo; Radius, Udo
• Is Part Of: European journal of inorganic chemistry. Volume 2022:Issue 31(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-09-22
• Subjects: Alkyl(amino)carbene -- EPR spectroscopy -- Metalloradicals -- N-heterocyclic Carbene -- Nickel ComplexCyclic; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.202200416
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: A series of five new homoleptic, linear nickel d 9 ‐complexes of the type [Ni I (NHC)2 ] + is reported. Starting from the literature known Ni(0) complexes [Ni(Mes2 Im)2 ] 1, [Ni(Mes2 Im H2 )2 ] 2, [Ni(Dipp2 Im)2 ] 3, [Ni(Dipp2 Im H2 )2 ] 4 and [Ni(cAAC Me )2 ] 5 (Mes2 Im=1, 3‐bis(2, 4, 6‐trimethylphenyl)‐imidazolin‐2‐ylidene, Mes2 Im H2 =1, 3‐bis(2, 4, 6‐trimethylphenyl)‐imidazolidin‐2‐ylidene, Dipp2 Im=1, 3‐bis(2, 6‐diisopropylphenyl)‐imidazolin‐2‐ylidene, Dipp2 Im H2 =1, 3‐bis(2, 6‐diisopropylphenyl)‐imidazolidin‐2‐ylidene, cAAC Me =1‐(2, 6‐diisopropylphenyl)‐3, 3, 5, 5‐tetramethylpyrrolidin‐2‐yliden), their oxidized Ni(I) analogues [Ni I (Mes2 Im)2 ][BPh4 ] 1 +, [Ni I (Mes2 Im H2 )2 ][BPh4 ] 2 +, [Ni I (Dipp2 Im)2 ][BPh4 ] 3 +, [Ni I (Dipp2 Im H2 )2 ][BPh4 ] 4 + and [Ni I (cAAC Me )2 ][BPh4 ] 5 + were synthesized by one‐electron oxidation with ferrocenium tetraphenyl‐borate. The complexes 1 + –5 + were fully characterized including X‐ray structure analysis. The complex cations reveal linear geometries in the solid state and NMR spectra with extremely broad, paramagnetically shifted resonances. DFT calculations predicted an orbitally degenerate ground state leading to large magnetic anisotropy, which was verified by EPR measurements in solution and on solid samples. The magnetic anisotropy of the complexes is highly dependent from the steric protection of the metal atom, which results in a noticeable decrease of the g ‐tensor anisotropy for the N ‐Mes substituted complexes 1 + and 2 + in solution due to the formation of T‐shaped THF adducts. Abstract : The synthesis and characterization of five new homoleptic, two‐coordinated linear nickel d 9 ‐complexes of the type [Ni I (NHC)2 ] + is reported. This study demonstrates the influence of NHC ligands on redox properties.