Highly reactive transition metal nitrides have received attention as key intermediates in nitrogen fixation, C-H bond activation and other catalytically relevant processes. Motivated by reports by Atienza et al. of a possible cobalt-nitride intermediate for benzylic C-H amination, we initiated a modeling study of methane functionalization by 3d metal nitrides. We utilized density functional (DFT) and MCSCF methods to study the electronic structure and reactivity of metal-nitridyl complexes supported by two NNN pincer-type ligands: monoanionic CztBu(PyriPr)2- and neutral 2,6-(PhN=CMe)2C5H3N. Calculations indicated that a low- to intermediate-spin metal-nitridyl intermediate with significant radical character on the nitridyl nitrogen can aminate aliphatic C-H bonds; the process is most energetically and kinetically favorable for cobalt and nickel complexes. These predictions were supported by independent experiments from the Thomson and Lee groups. A collaborative project with the Lee group led to an unprecedented example of double intramolecular C-H activation, which computations suggest occurs via a Ni-nitridyl intermediate.

Design of earth-abundant nitridyl catalysts for C-H functionalization

2019 Spring National Meeting

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