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-NSitBuMe2)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–Nimide bond distances (1.892(3) Å) with nearly equal Fe–Fe separation (2.483(1) Å).