Department of Chemistry and Center of Metals in Biocatalysis, University of Minnesota-Twin Cities, 207 Pleasant Street SE, Minneapolis, MN, 55455, USA.
Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, 15213, USA.
J Biol Inorg Chem. 2019 Jun;24(4):533-545. doi: 10.1007/s00775-019-01672-3. Epub 2019 Jun 6.
Oxoiron(IV) motifs are found in important intermediates in many enzymatic cycles that involve oxidations. Over half of the reported synthetic nonheme oxoiron(IV) analogs incorporate heterocyclic donors, with a majority of them comprising pyridines. Herein, we report H-NMR studies of oxoiron(IV) complexes containing pyridines that are arranged in different configurations relative to the Fe = O unit and give rise to paramagnetically shifted resonances that differ by as much as 50 ppm. The strong dependence of H-NMR shifts on the different configurations and orientation of pyridines relative to the oxoiron(IV) unit demonstrates how unpaired electronic spin density of the iron center affects the chemical shifts of these protons.
氧桥铁(IV)配合物存在于许多涉及氧化的酶循环的重要中间体中。已报道的合成非血红素氧桥铁(IV)类似物中超过一半的配合物含有杂环给体，其中大多数包含吡啶。在此，我们报告了含吡啶的氧桥铁(IV)配合物的 H-NMR 研究，吡啶相对于 Fe = O 单元以不同的构型排列，导致顺磁位移共振相差高达 50 ppm。H-NMR 位移对吡啶相对于氧桥铁(IV)单元的不同构型和取向的强烈依赖性表明，铁中心的未成对电子自旋密度如何影响这些质子的化学位移。
