Cis/Trans Isomerizations in Diiron Complexes Involving Aniline or Anilide Ligands

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• 作者：Eric Gour茅 ; Micha毛l Carboni ; Patrick Dubourdeaux ; Martin Cl茅mancey ; Ramachandran Balasubramanian ; Colette Lebrun ; Pierre-Alain Bayle ; Pascale Maldivi ; Genevi猫ve Blondin ; Jean-Marc Latour
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：October 6, 2014
• 年：2014
• 卷：53
• 期：19
• 页码：10060-10069
• 全文大小：540K
• ISSN：1520-510X

文摘

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, M枚ssbauer, and UV鈥搗isible 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 pK_a 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.