Abstract
The oxidation of light alkanes that is catalyzed by heme and nonheme iron enzymes is widely proposed to involve highly reactive {FeVO} species or {FeIVO} ligand cation radicals. The identification of these high-valent iron species and the development of an iron-catalyzed oxidation of light alkanes under mild conditions are of vital importance. Herein, a combination of tridentate and bidentate ligands was used for the generation of highly reactive nonheme {FeO} species. A method that employs [FeIII(Me3tacn)(Cl-acac)Cl]+ as a catalyst in the presence of oxone was developed for the oxidation of hydrocarbons, including cyclohexane, propane, and ethane (Me3tacn=1,4,7-trimethyl-1,4,7-triazacyclononane; Cl-acac=3-chloro-acetylacetonate). The complex [FeIII(Tp)2]+ and oxone enabled stoichiometric oxidation of propane and ethane. ESI-MS, EPR and UV/Vis spectroscopy, 18O labeling experiments, and DFT studies point to [FeIV(Me3tacn)({Cl-acac}.+)(O)]2+ as the catalytically active species.
Highly reactive {FeO} intermediates, such as [Fe(Tp)2(O)]+ or complex I (see Scheme), are likely to be involved in the oxidation of propane and ethane with oxone that is either mediated by [FeIII(Tp)2]+ (1) or catalyzed by iron complex 2. The cationic intermediate Ifeatures an {FeO} moiety and is stabilized by a combination of tridentate and bidentate ligands.
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Ligand Redox Noninnocence in [Co III (TAML)] 0/– Complexes Affects Nitrene Formation Nicolaas P. van Leest, Martijn A. Tepaske, Jean-Pierre H. Oudsen, Bas Venderbosch, Niels R. Rietdijk, Maxime A. Siegler, Moniek Tromp, Jarl Ivar van der Vlugt, and Bas de Bruin DOI: 10.1021/jacs.9b11715 J . Am. Chem. Soc. ASAP 訂正 雑誌会スライド8、9枚目の [Co III (TAML sq )] – の有効磁気モーメントの数値が [Co III (TAML red )] – のものになっていましたので、訂正致します。 誤: µ eff = 2.94 µ B ( S =1/2) 正: µ eff = 1.88 µ B ( S =1/2) Evans 法 NMR によって常磁性化合物の磁化率を求める方法。以下の式1– 5によって磁化率、有効磁気モーメントおよびスピン量子数 S が得られる。 以下は Supporting Information の記述である。 1. 常磁性種、内部標準を含んだ溶液を入れた NMR チューブの中に、内部標準だけを含んだ溶液を入れたキャピラリーを入れ、 NMR を測定する。 2. 内部標準のピークのシフト幅 Δν から磁化率 χ (cm 3 g -1 )を 計算する(式1)。 1 (ν 0 : 共鳴周波数、 c : 常磁性種の濃度、 M : 常磁性種のモル質量 ) 3. 磁化率 χ に M を 掛けること で、モル磁化率 χ M (cm 3 mol -1 )を 計算する(式2)。 ...
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