Jesse Kate A, Chang Mu-Chieh, Filatov Alexander S, Anderson John S
University of Chicago Department of Chemistry, 929 E 57 St. Chicago, IL, 60637.
National Taiwan University Department of Chemistry, No. 1, Section 4, Roosevelt Rd, Da'an District, Taipei City, Taiwan 10.
Z Anorg Allg Chem. 2021 Jul 27;647(14):1415-1420. doi: 10.1002/zaac.202100097. Epub 2021 May 27.
Nature uses control of the secondary coordination sphere to facilitate an astounding variety of transformations. Similarly, synthetic chemists have found metal-ligand cooperativity to be a powerful strategy for designing complexes that can mediate challenging reactivity. In particular, this strategy has been used to facilitate two electron reactions with first row transition metals that more typically engage in one electron redox processes. While NNN pincer ligands feature prominently in this area, examples which can potentially engage in both proton and electron transfer are less common. Dihydrazonopyrrole (DHP) ligands have been isolated in a variety of redox and protonation states when complexed to Ni. However, the redox-state of this ligand scaffold is less obvious when complexed to metal centers with more accessible redox couples. Here, we synthesize a new series of Fe-DHP complexes in two distinct oxidation states. Detailed characterization supports that the redox-chemistry in this set is still primarily ligand based. Finally, these complexes exist as 5-coordinate species with an open coordination site offering the possibility of enhanced reactivity.
自然界利用二级配位层的控制来促进种类惊人的各种转化。同样，合成化学家发现金属-配体协同作用是设计能够介导具有挑战性的反应性的配合物的有力策略。特别是，该策略已被用于促进与第一排过渡金属的双电子反应，而这些金属更典型地参与单电子氧化还原过程。虽然NNN钳形配体在这一领域占据显著地位，但可能同时参与质子和电子转移的例子却较少见。二肼基吡咯（DHP）配体在与镍络合时已被分离出多种氧化态和质子化状态。然而，当与具有更容易接近的氧化还原对的金属中心络合时，这种配体骨架的氧化态不太明显。在这里，我们合成了一系列处于两种不同氧化态的新型铁-DHP配合物。详细表征支持该系列中的氧化还原化学仍然主要基于配体。最后，这些配合物以五配位物种的形式存在，具有一个开放的配位位点，提供了增强反应性的可能性。
