Catalytic Silylation of Dinitrogen by a Family of Triiron Complexes

A series of triiron complexes supported by a tris­(β-diketiminate)­cyclophane (L3–) catalyze the reduction of dinitrogen to tris­(trimethylsilyl)­amine using KC8 and Me3SiCl. Employing Fe3Br3L 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)L as a common species in product mixtures. These results suggest that ancillary ligands can be abstracted with Lewis acids under reducing conditions.