Dinitrogen Activation Upon Reduction of a Triiron(II) Complex

Abstract Reaction of a trinuclear iron(II) complex, Fe 3 Br 3 L ( 1 ), with KC 8 under N 2 leads to dinitrogen activation products ( 2 ) from which Fe 3 (NH) 3 L ( 2‐1 ; L is a cyclophane bridged by three β‐diketiminate arms) was characterized by X‐ray crystallography. 1 H NMR spectra of the protonolysis product of 2 synthesized under 14 N 2 and 15 N 2 confirm atmospheric N 2 reduction, and ammonia is detected by the indophenol assay (yield ∼30 %). IR and Mössbauer spectroscopy, and elemental analysis on 2 and 2‐1 as well as the tri(amido)triiron(II) 3 and tri(methoxo)triiron 4 congeners support our assignment of the reduction product as containing protonated N‐atom bridges.