Modification of a Hexadentate Amine based Ligand System by N‐Methylation and Effects on Spin State and Redox Behavior of the Corresponding Transition Metal Complexes
Modification of a Hexadentate Amine based Ligand System by N‐Methylation and Effects on Spin State and Redox Behavior of the Corresponding Transition Metal Complexes
复制标题
N-甲基化对六齿胺基配体体系的修饰及其对相应过渡金属配合物自旋态和氧化还原行为的影响
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
Dieter Schaarschmidt
中科院分区：
文献类型：
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作者：
Silvio Heider;H. Petzold;J. Speck;T. Rüffer;Dieter Schaarschmidt
最近，本课题组合成了N，N′-双（2，2 ′-联吡啶-6-基甲基）-2，2 ′-联苯二胺（1a-d）及其铁（II）配合物（3a-d）。在这篇文章中，我们提出了类似的钴（II）配合物4a-d的合成。配合物3和配合物4与铁（II）配合物一起通过循环伏安法（CV）研究了其电化学行为。氨甲基亚结构被确定为与空气的化学氧化引起的配体降解的主要来源。在暴露于空气时，络合物3和4中的胺基被氧化成亚胺甚至酰胺基。通过X射线结构分析表征了氧化产物的一些实施例（8，9）。为了增加FeII和CoII复合物对氧化的鲁棒性，通过氨基的N-甲基化修饰1a的配体支架，得到叔胺2。以2为配体合成了相应的铁（II）和钴（II）配合物{[Fe（2）][PF 6]2（5），[Co（2）][PF 6]2（6）}，并对其进行了表征，用循环伏安法和Evans方法研究了它们的氧化还原行为和自旋态。据发现，引入的N-甲基导致MII-MIII氧化还原电位的大幅阳极偏移和Fe II和Co II高自旋态的稳定。通过X-射线结构分析，这些效应可以用甲基的排斥空间效应来解释。
Recently, the synthesis of hexadentate ligands based on N,N′-bis-(2,2′-bipyridine-6-ylmethyl)-2,2′-biphenylenediamine (1a–d) and the corresponding iron(II) complexes (3a–d) was reported by our group. In this contribution we present the synthesis of the analogous cobalt(II) complexes 4a–d. Together with the iron(II) complex the electrochemical behavior of the complexes 3 and 4 was investigated by cyclic voltammetry (CV). The aminomethyl substructure was identified as the main source of ligand degradation caused by chemical oxidation with air. Upon exposure to air the amine group in complexes 3 and 4 is oxidized to imine and even amide groups. Some examples (8, 9) of the oxidation products were characterized by X-ray structure analysis. In order to increase the robustness of the FeII and CoII complexes towards oxidation, the ligand scaffold of 1a was modified by N-methylation of the amino group yielding the tertiary amine 2. The corresponding iron(II) and cobalt(II) complexes employing 2 as ligand were synthesized {[Fe(2)][PF6]2 (5), [Co(2)][PF6]2 (6)} and fully characterized, their redox behavior and spin-state was investigated by CV and Evans' method. It was found, that the introduced N-methyl group leads to a substantial anodic shift of the MII–MIII redox potential and the stabilization of FeII and CoII high-spin state. By means of X-ray structure analysis these effects could be explained by repulsive steric effects of the methyl group.
2,5-二茂铁基-1-苯基-1 H-磷的合成和（光谱）电化学行为
影响因子：
2.8
作者：
D. Miesel;A. Hildebrandt;M. Korb;P.J. Low;H. Lang
通讯作者：
H. Lang
影响因子：
2.9
作者：
Chang, Cindy M.;Klema, Valerie J.;Johnson, Bryan J.;Mure, Minae;Klinman, Judith P.;Wilmot, Carrie M.
通讯作者：
Wilmot, Carrie M.