Oxidative Group Transfer to a Triiron Complex to Form a Nucleophilic μ3-Nitride, [Fe3(μ3-N)]−

Abstract

Utilizing a hexadentate ligand platform, a high-spin trinuclear iron complex of the type (^tbsL)Fe₃(thf) was synthesized and characterized ([^tbsL]⁶⁻ = [1,3,5-C₆H₉(NPh-o-NSi^tBuMe₂)₃]⁶⁻). The silyl-amide groups only permit ligation of one solvent molecule to the tri-iron core, resulting in an asymmetric core wherein each iron ion exhibits a distinct local coordination environment. The triiron complex (^tbsL)Fe₃(thf) rapidly consumes inorganic azide ([N₃]NBu₄) to afford an anionic, trinuclear nitride complex [(^tbsL)Fe₃(μ³-N)]NBu₄. The nearly C₃-symmetric complex exhibits a highly pyramidalized nitride ligand that resides 1.205(3) Å above the mean triiron plane with short Fe−N (1.871(3) Å) distances and Fe−Fe separation (2.480(1) Å). The nucleophilic nitride can be readily alkylated via reaction with methyl iodide to afford the neutral, trinuclear methylimide complex (^tbsL)Fe₃(μ³-NCH₃). Alkylation of the nitride maintains the approximate C₃-symmetry in the imide complex, where the imide ligand resides 1.265(9) Å above the mean triiron plane featuring lengthened Fe−N_imide bond distances (1.892(3) Å) with nearly equal Fe−Fe separation (2.483(1) Å).