Formation of stable and metastable porphyrin- and corrole-iron(IV) complexes and isomerizations to iron(III) macrocycle radical cations
Formation of stable and metastable porphyrin- and corrole-iron(IV) complexes and isomerizations to iron(III) macrocycle radical cations
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DOI：
10.1016/j.jinorgbio.2008.09.017
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发表时间：
2009-02-01
影响因子：
3.9
通讯作者：
Newcomb, Martin
中科院分区：
文献类型：
--
作者：
Pan, Zhengzheng;Harischandra, Dilusha N.;Newcomb, Martin
三种卟啉-铁（III）配合物(1)与高氯酸铁(Fe(ClO4)(3)在-40℃的乙腈溶液中氧化得到亚稳卟啉-铁（IV）二高氯酸配合物(2)，当溶液加热到室温时，这些配合物异构化成已知的铁（III）二高氯酸卟啉自由基阳离子(3)。采用紫外可见光谱法研究了5、10、15、20-四苯基卟啉（TPP）、5、10、15、20-四聚乙基卟啉（TMP）和2、3、7、8、12、13、17、18-八乙基卟啉（OEP）体系。低温核磁共振光谱和有效磁矩测量是可能的TPP和TMP铁（IV）配合物。研究了5,10,15-三（五氟苯基）络合物（TPFC）和5,15-二（五氟苯基）-10-对甲氧基苯基络合物（BPFMC）的反应。腐蚀铁（IV）氯化物与银盐反应生成腐蚀铁（IV）配合物。腐蚀-硝酸铁配合物在室温下是稳定的。（TPFC）-铁（IV）酯、(TPFC)-铁（IV）氯酸盐和(BPFMC)-铁（IV）氯酸盐是亚稳的，在室温下重排到它们的电子异构体铁（III）自由基阳离子上。（TPFC）-高氯酸铁（III）与高氯酸银反应的唯一产物是高氯酸铁(IV) -高氯酸铁（III）自由基阳离子。对于亚稳态铁（IV），在稀乙腈溶液中，铁（III）大环自由基阳离子电子异构体的异构化速率对大环配体的电子需求相对不敏感，但反映了配体对铁的结合强度。在不同温度和浓度下的动力学研究表明，异构化反应机制复杂，存在混阶反应。(C) 2008爱思唯尔公司版权所有。
Oxidations of three porphyrin-iron(III) complexes (1) with ferric perchlorate, Fe(ClO4)(3), in acetonitrile solutions at -40 degrees C gave metastable porphyrin-iron(IV) diperchlorate complexes (2) that isomerized to known iron(III) diperchlorate porphyrin radical cations (3) when the solutions were warmed to room temperature. The 5,10,15,20-tetraphenylporphyrin (TPP), 5,10,15,20-tetramesitylporphyrin (TMP), and 2,3,7,8,12,13,17,18-octaethylporphyrin (OEP) systems were studied by UV-visible spectroscopy. Low temperature NMR spectroscopy and effective magnetic moment measurements were possible with the TPP and TMP iron(IV) complexes. Reactions of two corrole systems, 5,10,15-tris(pentafluorophenyl)corrole (TPFC) and 5,15-bis(pentafluorophenyl)-10-p-methoxyphenylcorrole (BPFMC), also were studied. The corrole-iron(IV) chlorides reacted with silver salts to give corrole-iron(IV) complexes. The corrole-iron(IV) nitrate complexes were stable at room temperature. (TPFC)-iron(IV) toslyate, (TPFC)-iron(IV) chlorate, and (BPFMC)-iron(IV) chlorate were metastable and rearranged to their electronic isomers iron(III) corrole radical cations at room temperature. (TPFC)-iron(III) perchlorate corrole radical cation was the only product observed from reaction of the corrole-iron(IV) chloride with silver perchlorate. For the metastable iron(IV) species, the rates of isomerizations to the iron(III) macrocycle radical cation electronic isomers in dilute acetonitrile solutions were relatively insensitive to electron demands of the macrocyclic ligand but reflected the binding strength of the ligand to iron. Kinetic studies at varying temperatures and concentrations indicated that the mechanisms of the isomerization reactions are complex, involving mixed order reactivity. (C) 2008 Elsevier Inc. All rights reserved.