Biologically Relevant Heterodinuclear Iron鈥揗anganese Complexes

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• 作者：Micha毛l Carboni ; Martin Cl茅mancey ; Florian Molton ; Jacques P茅caut ; Colette Lebrun ; Lionel Dubois ; Genevi猫ve Blondin ; J.-M. Latour
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：October 1, 2012
• 年：2012
• 卷：51
• 期：19
• 页码：10447-10460
• 全文大小：611K
• 年卷期：v.51,no.19(October 1, 2012)
• ISSN：1520-510X

文摘

The heterodinuclear complexes [Fe^IIIMn^II(L-Bn)(渭-OAc)₂](ClO₄)₂ (1) and [Fe^IIMn^II(L-Bn)(渭-OAc)₂](ClO₄) (2) with the unsymmetrical dinucleating ligand HL-Bn {[2-bis[(2-pyridylmethyl)aminomethyl]]-6-[benzyl-2-(pyridylmethyl)aminomethyl]-4-methylphenol} were synthesized and characterized as biologically relevant models of the new Fe/Mn class of nonheme enzymes. Crystallographic studies have been completed on compound 1 and reveal an Fe^IIIMn^II渭-phenoxobis(渭-carboxylato) core. A single location of the Fe^III ion in 1 and of the Fe^II ion in 2 was demonstrated by M枚ssbauer and ¹H NMR spectroscopies, respectively. An investigation of the temperature dependence of the magnetic susceptibility of 1 revealed a moderate antiferromagnetic interaction (J = 20 cm^鈥?) between the high-spin Fe^III and Mn^II ions in 1, which was confirmed by M枚ssbauer and electron paramagnetic resonance (EPR) studies. The electrochemical properties of complex 1 are described. A quasireversible electron transfer at 鈭?0 mV versus Ag/AgCl corresponding to the Fe^IIIMn^II/Fe^IIMn^II couple appears in the cyclic voltammogram. Thorough investigations of the M枚ssbauer and EPR signatures of complex 2 were performed. The analysis allowed evidencing of a weak antiferromagnetic interaction (J = 5.72 cm^鈥?) within the Fe^IIMn^II pair consistent with that deduced from magnetic susceptibility measurements (J = 6.8 cm^鈥?). Owing to the similar value of the Fe^II zero-field splitting (D_Fe = 3.55 cm^鈥?), the usual treatment within the strong exchange limit was precluded and a full analysis of the electronic structure of the ground state of complex 2 was developed. This situation is reminiscent of that found in many diiron and iron鈥搈anganese enzyme active sites.