Iron nitrides have been found to be very attractive molecules due to their potential role in processes like Haber-Bosch and nitrogen fixation by nitrogenase. Our group reported the synthesis and characterization of the terminal iron nitride complex, [Ar*L]Fe(N)(py) (Ar*L = -[(Ar*N)2C(R)], Ar* = 2,6-bis(diphenylmethyl)-4-tert-butylphenyl, R = NCtBu2), stabilized by a “super-bulky” guanidinate ligand. Building upon this result, we have been investigating the synthesis of iron complexes supported by new super-bulky ligands HLAr’ (LAr’ = -[(Ar*N)2C(R)], R = methyl, piperidine, phenyl, tert-butyl, diisopropylamide. Utilizing protonolyis methods, reaction of HLAr’ with Fe2Mes4 produces the three-coordinate, organoiron complexes [LAr’]Fe(Mes). In the cases of [(Ar*N)2C(R)]Fe(Mes) (R = methyl, piperidine), these compounds react with hdbabh (hdbabh = (dbabh = 2,3:5,6-dibenzo-7-aza bicyclo[2.2.1]hepta-2,5-diene)), to give [(Ar*N)2C(Pip)]Fe(dbabh) and [(Ar*N)2C(Me)]Fe(dbabh)(hdbabh) in modest yields. Hdbabh is a well-established N-atom transfer reagent, which we intend to use for the synthesis of new terminal iron nitride products. Thermolysis of [(Ar*N)2C(Pip)]Fe(dbabh) and [(Ar*N)2C(Me)]Fe(dbabh)(hdbabh) does not lead to any observed reactivity; however, both compounds are photoactive. Photolysis of these compounds in solution lead to the formation of new paramagnetic species, which will be described in this presentation.

Sterically encumbering ligands for the targeted synthesis and stabilization of terminal Iron nitride

ACS Spring 2022

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