Premium
Evolution of Ate‐ Organoiron(II) Species towards Lower Oxidation States: Role of the Steric and Electronic Factors
Author(s) -
Rousseau Lidie,
Herrero Christian,
Clémancey Martin,
Imberdis Arnaud,
Blondin Geneviève,
Lefèvre Guillaume
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904228
Subject(s) - steric effects , chemistry , electrophile , reductive elimination , aryl , bimetallic strip , reactivity (psychology) , nucleophile , catalytic cycle , oxidation state , medicinal chemistry , photochemistry , oxidative addition , catalysis , electron paramagnetic resonance , quenching (fluorescence) , stereochemistry , organic chemistry , alkyl , medicine , alternative medicine , quantum mechanics , fluorescence , pathology , physics , nuclear magnetic resonance
Ate ‐iron(II) species such as [Ar 3 Fe II ] − (Ar=aryl) are key intermediates in Fe‐catalyzed couplings between aryl nucleophiles and organic electrophiles. They can be active species in the catalytic cycle, or lead to Fe 0 and Fe I oxidation states, which can themselves be catalytically active or lead to unwished organic byproducts. Analysis of the reactivity of the intermediates obtained by step‐by‐step displacement of the mesityl groups in high‐spin [Mes 3 Fe II ] − by less hindered phenyl ligands was performed, and uncovered the crucial role of both steric and electronic parameters in the formation of the Fe 0 and Fe I oxidation states. The formation of quaternized [Ar 4 Fe II MgBr(THF)] − intermediates allows the bielectronic reductive elimination energy required for the formation of Fe 0 to be reduced. Similarly, the small steric pressure of the aryl groups in [Ar 3 Fe II ] − enables the formation of aryl‐bridged [{Fe II (Ar) 2 } 2 (μ‐Ar) 2 ] 2− species, which afford the Fe I oxidation state by bimetallic reductive elimination. These results are supported by 1 H NMR, EPR, and 57 Fe Mössbauer spectroscopies, as well as by DFT calculations.