title: Cis/trans isomerizations in diiron complexes involving aniline or anilide ligands.
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.
authors.affiliation: CEA, iRTSV/LCBM, pmb , F-38000 Grenoble, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Gouré
authors.forename: Michaël
authors.initials: M
authors.lastname: Carboni
authors.forename: Patrick
authors.initials: P
authors.lastname: Dubourdeaux
authors.forename: Martin
authors.initials: M
authors.lastname: Clémancey
authors.forename: Ramachandran
authors.initials: R
authors.lastname: Balasubramanian
authors.forename: Colette
authors.initials: C
authors.lastname: Lebrun
authors.forename: Pierre-Alain
authors.initials: PA
authors.lastname: Bayle
authors.forename: Pascale
authors.initials: P
authors.lastname: Maldivi
authors.forename: Geneviève
authors.initials: G
authors.lastname: Blondin
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Latour