Max Planck Institut für Bioanorganische Chemie, 45470 Mülheim an der Ruhr, Germany.
Inorg Chem. 2010 Jun 21;49(12):5686-700. doi: 10.1021/ic100586h.
The redox properties of Fe and Zn complexes coordinated by an alpha-diimine based N(4)-macrocyclic ligand (TIM) have been examined using spectroscopic methods and density functional theory (DFT) computational analysis. DFT results on the redox series of Zn(TIM*) and Fe(TIM*) molecules indicate the preferential reduction of the alpha-diimine ligand moiety. In addition to the previously reported Fe(TIM*) dimer, we have now synthesized and characterized a further series of monomeric and dimeric complexes coordinated by the TIM ligand. This includes the five-coordinate monomeric [Fe(TIM*)I], the neutral and cationic forms of a monomeric phosphite adduct, [Fe(TIM*)(P(OPh)(3))] and Fe(TIM*)(P(OPh)(3)), as well as a binuclear hydroxy-bridged complex, {Fe(TIM*)}(2)(mu-OH). Experimental and computational data for these synthetic compounds denote the presence of ferrous and ferric species, suggesting that the alpha-diimine based macrocycles do not readily support the formation of formally low-valent (M(0) or M(I)) metal complexes as previously speculated. Magnetochemical, Mossbauer, electron paramagnetic resonance (EPR), and electronic spectral data have been employed to experimentally determine the oxidation state of the central metal ion and of the macrocyclic ligand (TIM*) in each compound. The series of compounds is described as follows: Fe(II)(TIM(0))(CH(3)CN(2)), S(Fe) = S(T) = 0; Fe(2.5)(TIM(2.5-)), S(T) = 1; {Fe(III)(TIM(2-))}(2)(mu-OH), S(Fe) = 3/2, S(T) = 0; [Fe(III)(TIM(2-))I], S(Fe) = 3/2, S(T) = 1/2; [Fe(II)(TIM(2-))(P(OPh(3)))], S(Fe) = S(T) = 0; and Fe(II)(TIM(1-))(P(OPh(3)))/Fe(I)(TIM(0))(P(OPh(3))), S(T) = 1/2. The results have been corroborated by DFT calculations.
基于α-二亚胺的 N(4)-大环配体（TIM）配位的 Fe 和 Zn 配合物的氧化还原性质已通过光谱方法和密度泛函理论（DFT）计算分析进行了研究。DFT 计算结果表明，Zn(TIM*)和Fe(TIM*)分子的氧化还原系列优先还原α-二亚胺配体部分。除了先前报道的Fe(TIM*)二聚体外，我们现在还合成并表征了一系列由 TIM 配体配位的单核和二核配合物。这包括五配位单核[Fe(TIM*)I]、单核膦酸酯加合物的中性和阳离子形式[Fe(TIM*)(P(OPh)(3))]和Fe(TIM*)(P(OPh)(3))，以及双核羟基桥联配合物{Fe(TIM*)}(2)(mu-OH)。这些合成化合物的实验和计算数据表明存在亚铁和铁物种，这表明基于α-二亚胺的大环不易支持形成先前推测的形式低价（M(0)或 M(I)）金属配合物。磁化学、穆斯堡尔谱、电子顺磁共振（EPR）和电子光谱数据已用于实验确定每个化合物中中心金属离子和大环配体（TIM*）的氧化态。该系列化合物描述如下：Fe(II)(TIM(0))(CH(3)CN(2))，S(Fe) = S(T) = 0；Fe(2.5)(TIM(2.5-))，S(T) = 1；{Fe(III)(TIM(2-))}(2)(mu-OH)，S(Fe) = 3/2，S(T) = 0；[Fe(III)(TIM(2-))I]，S(Fe) = 3/2，S(T) = 1/2；[Fe(II)(TIM(2-))(P(OPh(3)))]，S(Fe) = S(T) = 0；和Fe(II)(TIM(1-))(P(OPh(3)))/Fe(I)(TIM(0))(P(OPh(3)))，S(T) = 1/2。结果得到了 DFT 计算的证实。
