Related Experiment Video
Updated: Apr 23, 2026

Preparation of 6-aminocyclohepta-2,4-dien-1-one Derivatives via Tricarbonyltroponeiron
Published on: August 12, 2019
Cis/trans isomerizations in diiron complexes involving aniline or anilide ligands
Eric Gouré1, Michaël Carboni, Patrick Dubourdeaux
1CEA, iRTSV/LCBM, pmb , F-38000 Grenoble, France.
Abstract:
We have recently reported a deprotonation-induced valence inversion within a phenoxido-bridged mixed-valent diiron(II,III) complex. The initial aniline coordinated to the Fe(II) site reacts with triethylamine, and the resulting complex contains an anilide ligand coordinated to the Fe(III) ion. The behavior of these complexes in acetonitrile is indeed more intricate. Owing to the very distinctive spectroscopic signatures of the complexes, the conjunction of NMR, Mössbauer, and UV-visible absorption spectroscopies allows one to evidence two isomerization reactions, one involving the aniline linked to Fe(II) and the other the anilide on Fe(III). Theoretical calculations sustain this conclusion. Aniline in the cis position versus the bridging phenoxide is shown to be the most stable isomer while the anilide trans to the phenoxido bridge is favored. The trans isomer of the aniline complex is more acidic than the cis one by 1 pKa unit. Isomerization of the anilide complex is 10 times faster than the analogous isomerization of the aniline complex. Both reactions are proposed to proceed through a unique mechanism. This is the first time that such isomerization reactions are evidenced in dinuclear complexes.
More Related Videos
Related Concept Videos
Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly,...
Reduction of Alkynes to trans-Alkenes: Sodium in Liquid Ammonia
When dissolved in liquid ammonia, an alkali metal, such...
Disubstituted Cyclohexanes: cis-trans Isomerism
In cyclohexane, the substituents can occupy different positions generating distinct isomers....
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3

