Catalytic Silylation of Dinitrogen by a Family of Triiron Complexes

A series of triiron complexes supported by a tris­(β-diketiminate)­cyclophane (<b>L</b>^3–) catalyze the reduction of dinitrogen to tris­(trimethylsilyl)­amine using KC₈ and Me₃SiCl. Employing Fe₃Br₃<b>L</b> affords 83 ± 7 equiv of NH₄⁺/complex after protonolysis, which is a 50% yield, based on reducing equivalents. The series of triiron compounds tested evidence the subtle effects of ancillary donors, including halides, hydrides, sulfides, and carbonyl ligands, and metal oxidation state on N­(SiMe₃)₃ yield, and highlight Fe₃(μ₃-N)<b>L</b> as a common species in product mixtures. These results suggest that ancillary ligands can be abstracted with Lewis acids under reducing conditions