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