High‐Spin Imido Cobalt Complexes with Imidyl Radical Character

We report on the synthesis of a variety of trigonal imido cobalt complexes [Co(NAryl)L(2)](−), (L=N(Dipp)SiMe(3)), Dipp=2,6‐diisopropylphenyl) with very long Co−N(Aryl) bonds of around 1.75 Å. Their electronic structure was interrogated using a variety of physical and spectroscopic methods such as EPR or X‐Ray absorption spectroscopy which leads to their description as highly unusual imidyl cobalt complexes. Computational analyses corroborate these findings and further reveal that the high‐spin state is responsible for the imidyl character. Exchange of the Dipp substituent on the imide by the smaller mesityl function (2,4,6‐trimethylphenyl) effectuates the unexpected Me(3)Si shift from the ancillary ligand set to the imidyl nitrogen, revealing a highly reactive, nucleophilic character of the imidyl unit.