Influence of the Second Coordination Sphere on O2 Activation by a Nonheme Iron(II) Thiolate Complex

作者：Sudha Yadav, R. S. Lyons, Zoe Readi-Brown, Maxime A. Siegler, D. P. Goldberg · 发表于：Journal of Inorganic Biochemistry · 年份：2024 · DOI：10.1016/j.jinorgbio.2024.112776 · 被引用次数：5 · 研究领域：Medicine

The synthesis and characterization of a new 1-(bis(pyridin-2-ylmethyl) amino)-2-methylpropane-2-thiolate-ligated nonheme iron complex, FeII(BPAMe2S)Br (1), is reported. Reaction of 1 with O2 at −20 °C generates a high-spin iron(III)-hydroxide complex, [FeIII(OH)(BPAMe2S)(Br)] (2), that was characterized by UV-vis, 57Fe Mössbauer, and electron paramagnetic resonance (EPR) spectroscopies, and electrospray ionization mass spectrometry (ESI-MS). Density functional theory (DFT) calculations were employed to support the spectroscopic assignments. In a previous report (J. Am. Chem. Soc. 2024, 146, 7915 – 7921), the related bis((6-(neopentylamino) pyridinyl) methyl)amino)-2-methylpropane-2-thiolate-ligated iron(II) complex, FeII(BNPAMe2S)Br, was reported and shown to react with O2 at low temperature to give a rare (η2-superoxo)-iron(III) intermediate, which then converts to an S-oxygenated sulfinate as seen for the nonheme iron thiol dioxygenases. This complex includes two hydrogen bonding neopentylamino groups in the second coordination sphere. Complex 1 does not include these H-bonding groups, and its reactivity with O2 does not yield a stabilized Fe/O2 intermediate or S-oxygenated products, although the data suggest an inner-sphere mechanism and formation of an iron-oxygen species that is capable of abstracting hydrogen atoms from solvent or weak C-H bond substrates. This study indicates that the H-bond donors are critical for stabilizing the FeIII(O2−•) intermediate with the BNPA...