Engbers Silène, Guo Yisong, Klein Johannes E M N
Molecular Inorganic Chemistry, Stratingh Institute for Chemistry, Faculty of Science and Engineering, University of Groningen, Nijenborgh 4, 9747 AG, Groningen (The, Netherlands.
Department of Chemistry, Carnegie Mellon University, 4400 Fifth Ave, Pittsburgh, Pennsylvania, 15213, United States.
Angew Chem Int Ed Engl. 2023 Nov 13;62(46):e202313006. doi: 10.1002/anie.202313006. Epub 2023 Oct 10.
Isoporphyrins have recently been identified as remarkable species capable of turning the nucleophile attached to the porphyrin ring into an electrophile, thereby providing umpolung of reactivity (Inorg. Chem. 2022, 61, 8105-8111). They are generated by nucleophilic attack on an iron(III) π-dication, a class of species that has received scant attention. Here, we explore the effect of the porphyrin meso-substituent and report a iron(III) π-dication bearing the meso-tetraphenylporphyrin (TPP) ligand. We provide an extensive study of the species by UV/Vis absorption, H NMR, EPR, applied field Mössbauer, and resonance Raman spectroscopy. We further explore the system's highly dynamic and tunable properties and address the nature of the axial ligands as well as the conformation of the porphyrin ring. The insights presented are essential for the rational design of catalysts for the umpolung of nucleophiles. Such catalytic avenues could for example provide a novel method for electrophilic chlorinations. We further examine the importance of electronic tuning of the porphyrin by nature of the meso-substituent as a factor in catalyst design.
异卟啉最近被确认为是一类非凡的物种，能够将连接在卟啉环上的亲核试剂转化为亲电试剂，从而实现反应性的反转（《无机化学》，2022年，第61卷，8105 - 8111页）。它们是通过对铁（III）π - 二价阳离子进行亲核进攻而生成的，而这类物种很少受到关注。在此，我们研究了卟啉中位取代基的影响，并报道了一种带有中位四苯基卟啉（TPP）配体的铁（III）π - 二价阳离子。我们通过紫外/可见吸收光谱、¹H NMR、电子顺磁共振（EPR）、外加磁场穆斯堡尔谱和共振拉曼光谱对该物种进行了广泛研究。我们进一步探索了该体系高度动态且可调节的性质，并研究了轴向配体的性质以及卟啉环的构象。所提供的见解对于合理设计用于亲核试剂反转的催化剂至关重要。例如，这样的催化途径可以为亲电氯化反应提供一种新方法。我们还进一步研究了通过中位取代基的性质对卟啉进行电子调谐作为催化剂设计因素的重要性。
