Structural and Spectroscopic Characterization of a High-Spin {FeNO}(6) Complex with an Iron(IV)-NO(-) Electronic Structure.
Although the interaction of low-spin ferric complexes with nitric oxide has been well studied, examples of stable high-spin ferric nitrosyls (such as those that could be expected to form at typical non-heme iron sites in biology) are extremely rare. Using the TMG3 tren co-ligand, we have prepared a high-spin ferric NO adduct ({FeNO}(6) complex) via electrochemical or chemical oxidation of the corresponding high-spin ferrous NO {FeNO}(7) complex. The {FeNO}(6) compound is characterized by UV/Visible and IR spectroelectrochemistry, Mössbauer and NMR spectroscopy, X-ray crystallography, and DFT calculations. The data show that its electronic structure is best described as a high-spin iron(IV) center bound to a triplet NO(-) ligand with a very covalent iron-NO bond. This finding demonstrates that this high-spin iron nitrosyl compound undergoes iron-centered redox chemistry, leading to fundamentally different properties than corresponding low-spin compounds, which undergo NO-centered redox transformations.
Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, MI, 48109, USA.
Amy L
AL
Speelman
Department of Chemistry, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
Bo
B
Zhang
Department of Chemistry, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
Carsten
C
Krebs
Department of Chemistry, University of Michigan, 930 N University Avenue, Ann Arbor, MI, 48109, USA. lehnertn@umich.edu.
Nicolai
N
Lehnert
bioinorganic chemistry; enzyme models; nitric oxide; nitrogen oxides; non-heme iron