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Modelling the coordination environment in α‐ketoglutarate dependent oxygenases – a comparative study on the effect of N‐ vs. O‐ligation
Author(s) -
Warm Katrin,
Kass Dustin,
Haumann Michael,
Dau Holger,
Ray Kallol
Publication year - 2022
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.202100310
Subject(s) - ligand (biochemistry) , chemistry , oxygenase , carboxylate , stereochemistry , dioxygenase , chelation , heme , medicinal chemistry , enzyme , biochemistry , organic chemistry , receptor
In various non‐heme iron oxygenases the Fe(II) center is coordinated by 2 N and 1 O atoms of the 2‐His‐2‐carboxylate facial triad; however, most artificial model complexes bear only N‐based ligands. In an effort to closely mimic the coordination environment in α‐ketoglutarate dependent oxygenases, we have now employed the Me 2 tacnO ligand (4,7‐dimethyl‐1‐oxa‐4,7‐diazacyclononane) in the synthesis of the complexes [(Me 2 tacnO)FeCl 2 ] 2 ( 1‐NNO ), [(Me 2 tacnO)FeCl 3 ] ( 1 b‐NNO ) and [(Me 2 tacnO)Fe(BF)Cl] ( 2‐NNO ; BF=benzoylformate). The weaker donation of the O atom in the ligand was found to result in stronger binding of the ligand in trans ‐position to the O‐atom of the ancillary ligand as compared to the corresponding complexes involving the Me 3 tacn (1,4,7‐trimethyl‐1,4,7‐triazacyclononane) ligand. Furthermore, by stopped‐flow techniques we could detect an intermediate ( 3‐NNO ) in the reaction of 2‐NNO with O 2 . The spectroscopic features of 3‐NNO agree with the involvement of an Fe(IV)‐oxo intermediate and hence this study represents the first detection of such an intermediate in the O 2 activation of artificial α‐ketoglutarate Fe(II) complexes.