Wolves in Sheep's Clothing: μ‐Oxo‐Diiron Corroles Revisited |
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| Authors: | Sumit Ganguly Dr Hugo Vazquez‐Lima Prof?Dr Abhik Ghosh |
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| Affiliation: | Department of Chemistry and Center for Theoretical and Computational Chemistry, UiT – The Arctic University of Norway, Troms?, Norway |
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| Abstract: | For well over 20 years, μ‐oxo‐diiron corroles, first reported by Vogel and co‐workers in the form of μ‐oxo‐bis(octaethylcorrolato)iron] (Mössbauer δ 0.02 mm s?1, ΔEQ 2.35 mm s?1), have been thought of as comprising a pair antiferromagnetically coupled low‐spin FeIV centers. The remarkable stability of these complexes, which can be handled at room temperature and crystallographically analyzed, present a sharp contrast to the fleeting nature of enzymatic, iron(IV)‐oxo intermediates. An array of experimental and theoretical methods have now shown that the iron centers in these complexes are not FeIV but intermediate‐spin FeIII coupled to a corrole.2?. The intramolecular spin couplings in {FeTPC]}2(μ‐O) were analyzed via DFT(B3LYP) calculations in terms of the Heisenberg–Dirac–van Vleck spin Hamiltonian H=JFe–corrole(SFe?Scorrole)+JFe–Fe′(SFe?SFe′)+JFe′–corrole(SFe′?Scorrole′), which yielded JFe–corrole=JFe′–corrole′=0.355 eV (2860 cm?1) and JFe–Fe′=0.068 eV (548 cm?1). The unexpected stability of μ‐oxo‐diiron corroles thus appears to be attributable to charge delocalization via ligand noninnocence. |
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| Keywords: | corroles density functional calculations iron spin coupling structure elucidation |
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