Catytic N2 reduction to NH3 by a mononuclear Fe complex

Abstract

Our group has suggested that a hemi-labile role may be played by the interstitial light X-atom of the FeMocofactor, most recently assigned as C. Such a role would enable a high degree of conformational and redox flexibility at a single iron N_2 binding site. In particular, a hemi-labile behavior of the interstitial C-atom would allow an iron binding site to modulate its local geometry by varying its degree of interaction with the C-atom under crude local three-fold symmetry, possibly sampling trigonal bipyramidal, trigonal pyramidal, and/or pseudotetrahedral geometries as a function of the nature of the state of redn. of the nitrogenous ligand. To test these ideas, our group has been exploring a range of 4- and 5-coordinate iron model complexes that exhibit local three-fold symmetry and feature a host of nitrogenous ligands (e.g., N_2, N_2H_4, NH_3, NH_(2-), NR^(2-), N^(3-)) in an axial substrate-binding site trans to a light atom (e.g., B or C). These single-iron site inorg. model complexes show promise for the catalytic redn. of nitrogen to ammonia in the presence of protons and electrons in soln. at low temp. This talk will provide an update on our lab's most recent progress in this area.