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Non‐Heme Fe II Diastereomeric Complexes Bearing a Hexadentate Ligand: Unexpected Consequences for the Spin State and Catalytic Oxidation Properties
Author(s) -
SénéchalDavid Katell,
Buron Charlotte,
Ségaud Nathalie,
Rebilly JeanNoël,
Dos Santos Amandine,
Farjon Jonathan,
Guillot Régis,
Herrero Christian,
Inceoglu Tanya,
Banse Frédéric
Publication year - 2019
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.201902423
Subject(s) - chemistry , steric effects , ligand (biochemistry) , diastereomer , catalysis , reactivity (psychology) , selectivity , spin states , stereochemistry , medicinal chemistry , diamine , lability , oxidation state , anisole , crystallography , polymer chemistry , inorganic chemistry , organic chemistry , medicine , biochemistry , receptor , alternative medicine , pathology
The reactivity and selectivity of non‐heme Fe II complexes as oxidation catalysts can be substantially modified by alteration of the ligand backbone or introduction of various substituents. In comparison with the hexadentate ligand N , N , N ′, N ′‐tetrakis(pyridin‐2‐ylmethyl)ethane‐1,2‐diamine (TPEN), N , N ′‐bis[1‐(pyridin‐2‐yl)ethyl]‐ N , N ′‐bis(pyridin‐2‐ylmethyl)ethane‐1,2‐diamine ( 2Me L 6 2 ) has a methyl group on two of the four picolyl positions. Fe II complexation by 2Me L 6 2 yields two diastereomeric complexes with very similar structures, which only differ in the axial/equatorial positions occupied by the methylated pyridyl groups. In solution, these two isomers exhibit different magnetic behaviors. Whereas one isomer exhibits temperature‐dependent spin‐state conversion between the S =0 and S =2 states, the other is more reluctant towards this spin‐state equilibrium and is essentially diamagnetic at room temperature. Their catalytic properties for the oxidation of anisole by H 2 O 2 are very different and correlate with their magnetic properties, which reflect their lability/inertness. These different properties most likely depend on the different steric constraints of the methylated pyridyl groups in the two complexes.