title: A Terminal N2 Complex of High-Spin Iron(I) in a Weak, Trigonal Ligand Field.
abstract: The role of Fe in biological and industrial N2 fixation has inspired the intense study of small molecule analogues of Fe-(NxHy) intermediates of potential relevance to these processes. Although a number of low-coordinate Fe-(N2) featuring varying degrees of fidelity to the nitrogenase active site are now known, these complexes frequently feature strongly donating ligands that either enforce low- or intermediate-spin states or result in linear Fe-(N2)-Fe bridging motifs. Given that the nitrogenase active site uses weak-field sulfide ligands to stabilize its reactive Fe center(s), N2 binding to high-spin Fe is of great interest. Herein, we report the synthesis and characterization of the first terminal N2 complex of high-spin (S = 3/2) Fe(I) as well as a bridging Fe-(N2)-Fe analogue. Electron paramagnetic resonance and solution magnetic moment determination confirm the high-spin state, and vibrational experiments indicate a substantial degree of activation of the N≡N bond in these complexes. Density functional theory calculations reveal an electronic structure for the terminal adduct featuring substantial delocalization of unpaired spin onto the N2 ligand.
authors.affiliation: Department of Chemistry, University of California, Riverside, California 92521, United States.
authors.forename: Alex
authors.initials: A
authors.lastname: McSkimming
authors.affiliation: Department of Chemistry, University of California, Riverside, California 92521, United States.
authors.forename: W Hill
authors.initials: WH
authors.lastname: Harman
mesh_terms: D020134:Catalytic Domain; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D058085:Iron Compounds / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D009584:Nitrogen / Q000737:chemistry*; D009591:Nitrogenase / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D058085:Iron Compounds; D008024:Ligands; D009591:Nitrogenase; D009584:Nitrogen