Catalytic conversion of nitrogen to ammonia by a single-site Fe model complex

Nitrogen redn. to ammonia is one of the most fascinating chem. transformations mediated in biol. While it is widely appreciated that the iron- rich cofactors of nitrogenase enzymes facilitate this transformation, how they do so remains a mystery. Inorg. model complexes afford one approach to consider and test the viability of mechanistic proposals. Herein we describe a well- defined tris- phosphine borane iron catalyst that is able to catalyze the redn. of N to NH by the addn. of protons and electrons at - 78 °C. A key design element of the featured catalyst is a hemi- labile ligand that may functionally model the interstitial light C- atom of the nitrogenase cofactor. The results described suggest that a single- iron- sitehypothesis for biol. nitrogenfixation warrants further consideration