Coordination of carboxamido nitrogen to tervalent iron: insight into a new chapter of iron chemistry

Iron(III) Complexes with the Ligand N′,N′‐Bis[(2‐pyridyl)methyl]ethylenediamine (uns‐penp) and Its Amide Derivative N‐Acetyl‐N′,N′‐bis[(2‐pyridyl)methyl]ethylenediamine (acetyl‐uns‐penp)

“…Besides the hydrogen bonding, the crystal structure shows no extraordinary features. Furthermore, iron complexation with carboxamide ligands has attracted the interest of inorganic chemists to gain better understanding of metal-peptide bond coordination chemistry in life sciences [20] and to use such complexes as model compounds for the anti-tumor drug bleomycin [21,22] or nitrile hydratase. [23][24][25] Important in that regard are the results reported by Mascharak and co-workers, who have investigated in detail the structures and properties of Fe II /Fe III complexes of a number of carboxamide ligands, several based on a pyridine-2-carboxamide framework, e.g.…”

Change in the Spin State of an FeIII Center upon One N‐to‐O Switch in the Coordination of a 2,6‐Pyridinedicarboxamido Unit: The Effect of Methyl Thioether and Methyl Ether Appendages at the Ligand Periphery

“…[7,8,9] In addition, it appears that Fe III complexes with Fe III ϪN amido bonds are resistant toward hydrolysis despite the common belief that the highly basic carboxamido nitrogens could be readily attacked by water. Collectively, these results indicate that carboxamido nitrogens have a high affinity for Fe III centers and impart stability towards hydrolysis of the resultant complexes.…”

“…Indeed, coordination of this group results in highly negative E 1/2 values (up to Ϫ1.10 V) indicating that carboxamido nitrogens provide significant stability to iron in the ϩ3 oxidation state. [7] Furthermore, the majority of Fe III complexes coordinated to one, two, or four carboxamido nitrogens contain low spin Fe III cen-mer fashion. In this case, however, less steric crowding among the smaller pendant ether groups allows binding of all four carboxamido nitrogens to the Fe III center in [Fe(PyPOMe) 2 ] − giving rise to an FeN 6 chromophore.…”

Synthetic Analogues of the Active Site of the A-Cluster of Acetyl Coenzyme A Synthase/CO Dehydrogenase: Syntheses, Structures, and Reactions with CO

“…21,26,[31][32][33] Coordination of deprotonated carboxamido nitrogen to metal centers is readily indicated by the red-shift of the carbonyl stretching frequency (ν co ) of the complex with respect to the ν co of the free ligand. 34 Complex 2 exhibits its ν co at 1521 cm -1 compared to 1652 cm -1 for the free ligand PhPepSH 4 . In MeCN, 2 exhibits a dark-red color arising from strong ligand-tometal charge transfer absorption at 384 nm and a d-d band at 545 nm typical for Ni(II) complexes with dicarboxamido-dithiolato (N 2 S 2 ) coordination.…”