Reactivity of a Bis(amidinato)iron(II) Complex [Fe(MesC(NPri)2)2] toward Some Oxidizing Reagents
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A diversified reactivity of the mononuclear bis(amidinato)iron(II) complex [Fe(MesC(NPri)2)2] (1) toward oxidizing reagents has been disclosed. The bis(amidinato)iron(II) complex was synthesized from the reaction of [Fe(Mes)2]2 with 4 equiv of diisopropyl carbodiimide in good yield. Treatment of 1 with 1 equiv of benzyl chloride gives the high-spin ferric complex [FeCl(MesC(NPri)2)2] (2), with 0.25 equiv of S8 affords the sulfur-insertion product [Fe(MesC(NPri)(NPriS))2] (3), with 1 equiv of 3,5-dimethylphenyl azide or phenyl azide yields nitrene-insertion product [Fe(MesC(NPri)2)(PriNC(Mes)N(Pri)NAr)] (Ar = 3,5-dimethylphenyl, 4a; phenyl, 4b), and with 1 equiv of oxo-transfer reagent, trimethylamine oxide or 2,6-dichloropyridine oxide, generates the oxo-bridged diferric complex [(MesC(NPri)2)2FeOFe(MesC(NPri)2)2] (5). Complexes 1–3, 4a, and 5 have been characterized by 1H NMR, UV–vis, IR, elemental analysis, and single-crystal X-ray diffraction studies. The formations of these unusual sulfur- and nitrene-insertion products 3, 4a, and 4b, can be explained by the sequential redox reaction between 1 and the oxidants, followed by migratory insertion steps.
本研究报道了单核双(脒基)铁(II)配合物（mononuclear bis(amidinato)iron(II) complex）[Fe(MesC(NPri)₂)₂]（1，其中Mes为均三甲苯基（mesityl），Pri为异丙基（isopropyl））与氧化剂的多样反应性。该双(脒基)铁(II)配合物可通过[Fe(Mes)₂]₂与4当量二异丙基碳二亚胺（diisopropyl carbodiimide）反应合成，且产率优良。将配合物1与1当量苄氯（benzyl chloride）反应，可得到高自旋三价铁配合物（high-spin ferric complex）[FeCl(MesC(NPri)₂)₂]（2）；与0.25当量单质硫（Sulfur, S₈）反应则生成硫插入产物（sulfur-insertion product）[Fe(MesC(NPri)(NPriS))₂]（3）；与1当量3,5-二甲基苯基叠氮（3,5-dimethylphenyl azide）或苯基叠氮（phenyl azide）反应，可得到氮宾插入产物（nitrene-insertion product）[Fe(MesC(NPri)₂)(PriNC(Mes)N(Pri)NAr)]（Ar=3,5-二甲基苯基（3,5-dimethylphenyl），4a；苯基（phenyl），4b）；与1当量氧转移试剂（oxo-transfer reagent，如三甲基胺N-氧化物（trimethylamine oxide）或2,6-二氯吡啶N-氧化物（2,6-dichloropyridine oxide））反应，则生成氧桥联二铁(III)配合物（oxo-bridged diferric complex）[(MesC(NPri)₂)₂FeOFe(MesC(NPri)₂)₂]（5）。配合物1~3、4a及5均通过¹H核磁共振波谱（¹H NMR）、紫外-可见吸收光谱（UV–vis）、红外光谱（IR）、元素分析（elemental analysis）及单晶X射线衍射（single-crystal X-ray diffraction）进行了结构表征。上述罕见的硫插入与氮宾插入产物3、4a及4b的生成过程，可通过配合物1与氧化剂依次发生氧化还原反应（redox reaction），随后经历迁移插入步骤（migratory insertion steps）予以阐释。
