Harischandra Dilusha N, Zhang Rui, Newcomb Martin
Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, Illinois 60607, USA.
J Am Chem Soc. 2005 Oct 12;127(40):13776-7. doi: 10.1021/ja0542439.
Laser flash photolysis of 5,10,15-tris(pentafluorophenyl)corrole-iron(IV) chlorate or nitrate, prepared from the corresponding chloride, gave a highly reactive iron-oxo transient identified as an iron(V)-oxo species on the basis of its UV-visible spectrum and high reactivity as well as by analogy to photochemical ligand cleavage reactions of related manganese species. The transient was shown to be an oxo transfer agent in a preparative reaction with cis-cyclooctene. Representative rate constants for oxidation reactions by the new transient at ambient temperature were k = 5900 M-1 s-1 for cyclooctene and k = 570 M-1 s-1 for ethylbenzene. The new transient is more than 6 orders of magnitude more reactive with typical organic reductants than expected for an iron(IV)-oxo corrole radical cation and 100 times more reactive than an analogous positively charged iron(IV)-oxo porphyrin radical cation. Slow electron transfer isomerization of ligand iron(V)-oxo species to iron(IV)-oxo ligand radical cations might be important in reactions of porphyrin-iron catalysts in the laboratory and in nature.
由相应的氯化物制备的5,10,15-三（五氟苯基）卟啉-铁（IV）氯酸盐或硝酸盐经激光闪光光解后，产生了一种高活性的铁-氧瞬态物种。基于其紫外可见光谱、高反应活性以及与相关锰物种光化学配体裂解反应的类比，该瞬态物种被确定为铁（V）-氧物种。在与顺式环辛烯的制备反应中，该瞬态物种被证明是一种氧转移剂。在环境温度下，新瞬态物种氧化反应的代表性速率常数为：环辛烯的k = 5900 M-1 s-1，乙苯的k = 570 M-1 s-1。与典型的有机还原剂反应时，新瞬态物种的反应活性比预期的铁（IV）-氧卟啉自由基阳离子高6个数量级以上，比类似的带正电荷的铁（IV）-氧卟啉自由基阳离子高100倍。配体铁（V）-氧物种向铁（IV）-氧配体自由基阳离子的慢电子转移异构化在实验室和自然界中卟啉-铁催化剂的反应中可能很重要。
