Catalytic Silylation of Dinitrogen by a Family of Triiron Complexes.

A series of triiron complexes supported by a tris(β-diketiminate)cyclophane (L 3- ) catalyze the reduction of dinitrogen to tris(trimethylsilyl)amine using KC8 and Me3SiCl. Employing Fe3Br3 L affords 83 ± 7 equiv. NH4 +/complex after protonolysis, which is a 50% yield based on reducing equivalents. The series of triiron compounds tested evidences 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.