The formation of new N–C bonds directly from dinitrogen (N2) enables more efficient strategies towards the synthesis of organic compounds. Performing such N2 functionalization chemistry using sustainable, first-row metals has proven challenging using carbon electrophiles. In a new approach, our group has developed a system which can aminate C–H bonds of unactivated arenes directly from N2 in a cyclic fashion mediated by a low-valent β-diketiminate supported iron complex, with the potential for catalytic turnover. We proposed that the N–C bond formation step occurs after silylation of iron-bound N2 to give a formally iron(IV) hydrazido species which subsequently undergoes migratory insertion of the aryl group to the hydrazido group, but this intermediate was not observed. Here, the mechanism of this key step is studied both experimentally, using variation of the silyl and hydrocarbyl groups, and computationally using density functional theory calculations. Notable advances are the ability to arrest the reaction at the hydrazido species, and an assessment of the barriers for migratory insertion in different spin state manifolds.

Migratory insertion of hydrocarbyl groups to dinitrogen via a high-valent iron(IV) hydrazido intermediate

ACS Spring Meeting 2021

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