Reactivity of a Fe(III)-Bound Methoxide Supported with a Tris(thiolato)phosphine Ligand: Activation of C–Cl Bond in CH2Cl2 by Nucleophilic Attack of a Fe(III)–OCH3 Moiety

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• 作者：Kai-Chun Chang ; Ching-Ju Huang ; Ya-Ho Chang ; Zong-Han Wu ; Ting-Shen Kuo ; Hua-Fen Hsu
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：January 19, 2016
• 年：2016
• 卷：55
• 期：2
• 页码：566-572
• 全文大小：413K
• ISSN：1520-510X

文摘

Two mononuclear nonheme Fe^III complexes, [PPh₄][Fe^III(PS3″)(OCH₃)] (1) and [PPh₄][Fe^III(PS3″)(Cl)] (2), supported by a tris(benzenethiolato)phosphine derivative PS3″ (PS3″ = P(C₆H₃-3-Me₃Si-2-S)₃^3–) have been synthesized and characterized. The structures resolved from X-ray crystallography show that Fe^III centers in both complexes adopt distorted trigonal-bipyramidal geometry with a methoxide or a chloride binding in the axial position. The magnetic data for both are consistent with intermediate-spin Fe^III centers with a C₃ symmetry (S = 3/2 ground state). The bound methoxide in 1 is labile and can be replaced by a CH₃CN molecule. The forming Fe^III–CH₃CN species can be further reduced by cobaltcene quantitatively to a stable Fe^II–CH₃CN complex, [Fe(PS3″)(CH₃CN)]^?. One-electron oxidation of 2 by ferrocenium gave a Fe^IV analogue, [Fe^IV(PS3″)(Cl)]. Importantly, the Fe^III–OCH₃ moiety in complex 1 acts as a strong nucleophile that activates the C–Cl bond in CH₂Cl₂, leading to the formation of complex 2 quantitatively. Complex 1 also reacts with other electrophiles, benzyl chloride and benzyl bromide, to generate Fe^III–X species (X = Cl or Br). The reactions were investigated and monitored by UV–vis–NIR, NMR, and ESI-MS spectroscopies.