Versatile Reactivity of a Solvent-Coordinated Diiron(II) Compound: Synthesis and Dioxygen Reactivity of a Mixed-Valent FeIIFeIII Species
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- 作者：Amit Majumdar ; Ulf-Peter Apfel ; Yunbo Jiang ; Pierre Mo?nne-Loccoz ; Stephen J. Lippard
- 刊名：Inorganic Chemistry
- 出版年：2014
- 出版时间：January 6, 2014
- 年：2014
- 卷：53
- 期：1
- 页码：167-181
- 全文大小：916K
- ISSN：1520-510X
文摘
A new, DMF-coordinated, preorganized diiron compound [Fe2(N-Et-HPTB)(DMF)4](BF4)3 (1) was synthesized, avoiding the formation of [Fe(N-Et-HPTB)](BF4)2 (10) and [Fe2(N-Et-HPTB)(渭-MeCONH)](BF4)2 (11), where N-Et-HPTB is the anion of N,N,N鈥?N鈥?tetrakis[2-(1-ethylbenzimidazolyl)]-2-hydroxy-1,3-diaminopropane. Compound 1 is a versatile reactant from which nine new compounds have been generated. Transformations include solvent exchange to yield [Fe2(N-Et-HPTB)(MeCN)4](BF4)3 (2), substitution to afford [Fe2(N-Et-HPTB)(渭-RCOO)](BF4)2 (3, R = Ph; 4, RCOO = 4-methyl-2,6-diphenyl benzoate]), one-electron oxidation by (Cp2Fe)(BF4) to yield a Robin鈥揇ay class II mixed-valent diiron(II,III) compound, [Fe2(N-Et-HPTB)(渭-PhCOO)(DMF)2](BF4)3 (5), two-electron oxidation with tris(4-bromophenyl)aminium hexachloroantimonate to generate [Fe2(N-Et-HPTB)Cl3(DMF)](BF4)2 (6), reaction with (2,2,6,6-tetramethylpiperidin-1-yl)oxyl to form [Fe5(N-Et-HPTB)2(渭-OH)4(渭-O)(DMF)2](BF4)4 (7), and reaction with dioxygen to yield an unstable peroxo compound that decomposes at room temperature to generate [Fe4(N-Et-HPTB)2(渭-O)3(H2O)2](BF4)路8DMF (8) and [Fe4(N-Et-HPTB)2(渭-O)4](BF4)2 (9). Compound 5 loses its bridging benzoate ligand upon further oxidation to form [Fe2(N-Et-HPTB)(OH)2(DMF)2](BF4)3 (12). Reaction of the diiron(II,III) compound 5 with dioxygen was studied in detail by spectroscopic methods. All compounds (1鈥?b>12) were characterized by single-crystal X-ray structure determinations. Selected compounds and reaction intermediates were further examined by a combination of elemental analysis, electronic absorption spectroscopy, M枚ssbauer spectroscopy, EPR spectroscopy, resonance Raman spectroscopy, and cyclic voltammetry.