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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(15):4369-4373
The development of iron catalysts for carbon–heteroatom bond formation, which has attracted strong interest in the context of green chemistry and nitrene transfer, has emerged as the most promising way to versatile amine synthetic processes. A diiron system was previously developed that proved efficient in catalytic sulfimidations and aziridinations thanks to an FeIIIFeIV active species. To deal with more demanding benzylic and aliphatic substrates, the catalyst was found to activate itself to a FeIIIFeIVL. active species able to catalyze aliphatic amination. Extensive DFT calculations show that this activation event drastically enhances the electron affinity of the active species to match the substrates requirements. Overall this process consists in a redox self‐adaptation of the catalyst to the substrate needs. 相似文献
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Jai Prakash Yuan Sheng Apparao Draksharapu Johannes E. M. N. Klein Christopher J. Cramer Lawrence Que 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(7):2017-2021
The syn and anti isomers of [FeIV(O)(TMC)]2+ (TMC=tetramethylcyclam) represent the first isolated pair of synthetic non‐heme oxoiron(IV) complexes with identical ligand topology, differing only in the position of the oxo unit bound to the iron center. Both isomers have previously been characterized. Reported here is that the syn isomer [FeIV(Osyn)(TMC)(NCMe)]2+ ( 2 ) converts into its anti form [FeIV(Oanti)(TMC)(NCMe)]2+ ( 1 ) in MeCN, an isomerization facilitated by water and monitored most readily by 1H NMR and Raman spectroscopy. Indeed, when H218O is introduced to 2 , the nascent 1 becomes 18O‐labeled. These results provide compelling evidence for a mechanism involving direct binding of a water molecule trans to the oxo atom in 2 with subsequent oxo–hydroxo tautomerism for its incorporation as the oxo atom of 1 . The nonplanar nature of the TMC supporting ligand makes this isomerization an irreversible transformation, unlike for their planar heme counterparts. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(36):11021-11025
Reactions of the BH4− anion with equimolar amounts of HN(NO2)2 or of BH3⋅THF with K[N(NO2)2]− produced a mono‐substituted [BH3N(NO2)2]− anion, which contains a B−N connected dinitramido ligand. The reaction of BH4− with two equivalents of HN(NO2)2 afforded the di‐substituted borate anion consisting of two isomers, one with both nitramido ligands attached to B through N and the other one with one ligand attached through N and the other one through O. The disubstituted dinitramidoborates are marginally stable under ambient conditions, and the isomer with two N‐connected ligands was characterized by its crystal structure. A tri‐substituted borate was tentatively identified by NMR in the reaction of BH4− with a large excess of HN(NO2)2. All of the anions are highly energetic. Theoretical calculations show that the energy differences between the B−N and B−O tautomers are small, explaining the formation of both. 相似文献
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