Cationic Nickel d⁹‐Metalloradicals [Ni(NHC)₂]⁺

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