Generation of a High-Valent Iron Imido Corrolazine Complex and NR Group Transfer Reactivity
Generation of a High-Valent Iron Imido Corrolazine Complex and NR Group Transfer Reactivity
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DOI：
10.1021/ic400280x
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发表时间：
2013-04-15
影响因子：
4.6
通讯作者：
Goldberg, David P.
中科院分区：
文献类型：
--
作者：
Leeladee, Pannee;Jameson, Guy N. L.;Goldberg, David P.
本文报道了一种新型的高价铁末端亚胺配合物的生成。[Fe-III(TBP(8)Cz)] (TBP（8)Cz = octakis（4-叔丁基苯基）腐蚀物）与市售氯胺-t （Na+TsNCl-）在室温下在二氯甲烷/乙腈中发生N-tosyl氧化转移生成[Fe-IV(TBP（8)Cz（+中心点））（NTs）]。通过紫外可见光谱、穆斯堡尔光谱（δ = -0.05 mm s（-1）、δ E-Q = 2.94 mm s(-1)）和EPR光谱（x波段（15 K）， g = 2.10, 2.00）对该配合物进行了表征，并结合反应性谱图和DFT计算，确定该配合物为铁（IV）种，具有反铁磁偶联的cz -阳离子自由基（s -total = 1/2基态）。以三苯基膦为底物的反应性研究表明，[Fe-IV(TBP（8)Cz（+中心点））（NTs）]是一种高效的NTs转移剂，在化学计量和催化条件下都能生成Ph3P=NTs的磷烷产物。该反应的动力学分析支持速率常数为70(15)M-1 s（-1）的双分子NTs转移机制。这些数据表明，[Fe-IV(TBP（8)Cz（+中心点））（NTs）]的反应速度比类似的Mn末端芳基缀合物快约100倍。结果表明，Fe-III(TBP(8)Cz) +氯胺- t + PPh3的反应混合物结晶为[Fe-IV(TBP(8)Cz)(NPPh3)]和[Fe-III(TBP(8)Cz)(OPPh3)]，并用x射线晶体学对其进行了明确的表征。通过P-31核磁共振光谱观察到Ph3P=NTs, Ph3P=NH和Ph3P=O的顺序产生，并提出了一个解释所有观察到的产物的机制。以Fe-III（TBP(8)Cz）和OPPh3为原料合理合成Fe-III配合物并进行结构表征，为光谱研究提供了重要的基准化合物。结合穆斯堡尔光谱和EPR光谱，得到了中间自旋（S = 3/2）和低自旋（S = 1/2）的Fe-III腐蚀嗪，以及一种形式上的Fe-IV腐蚀嗪，它也可以用它的价互变异构体Fe-III（Cz（+中心点））来描述。
The generation of a new high-valent iron terminal imido complex prepared with a corrolazine macrocycle is reported. The reaction of [Fe-III(TBP(8)Cz)] (TBP(8)Cz = octakis(4-tert-butylphenyl)corrolazinato) with the commercially available chloramine-T (Na+TsNCl-) leads to oxidative N-tosyl transfer to afford [Fe-IV(TBP(8)Cz(+center dot))(NTs)] in dichloromethane/acetonitrile at room temperature. This complex was characterized by UV-vis, Mossbauer (delta = -0.05 mm s(-1), Delta E-Q = 2.94 mm s(-1)), and EPR (X-band (15 K), g = 2.10, 2.00) spectroscopies, and together with reactivity patterns and DFT calculations has been established as an iron(IV) species antiferromagnetically coupled with a Cz-pi-cation-radical (S-total = 1/2 ground state). Reactivity studies with triphenylphosphine as substrate show that [Fe-IV(TBP(8)Cz(+center dot))(NTs)] is an efficient NTs transfer agent, affording the phospharane product Ph3P=NTs under both stoichiometric and catalytic conditions. Kinetic analysis of this reaction supports a bimolecular NTs transfer mechanism with rate constant of 70(15) M-1 s(-1). These data indicate that [Fe-IV(TBP(8)Cz(+center dot))(NTs)] reacts about 100 times faster than analogous Mn terminal arylimido corrole analogues. It was found that two products crystallize from the same reaction mixture of Fe-III(TBP(8)Cz) + chloramine-T + PPh3, [Fe-IV(TBP(8)Cz)(NPPh3)] and [Fe-III(TBP(8)Cz)(OPPh3)], which were definitively characterized by X-ray crystallography. The sequential production of Ph3P=NTs, Ph3P=NH, and Ph3P=O was observed by P-31 NMR spectroscopy and led to a proposed mechanism that accounts for all of the observed products. The latter Fe-III complex was then rationally synthesized and structurally characterized from Fe-III(TBP(8)Cz) and OPPh3, providing an important benchmark compound for spectroscopic studies. A combination of Mossbauer and EPR spectroscopies led to the characterization of both intermediate spin (S = 3/2) and low spin (S = 1/2) Fe-III corrolazines, as well as a formally Fe-IV corrolazine which may also be described by its valence tautomer Fe-III(Cz(+center dot)).