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<sup>IIIsup> complexes, [PPh<sub>4sub>][Fe<sup>IIIsup>(PS3″)(OCH<sub>3sub>)] (1) and [PPh<sub>4sub>][Fe<sup>IIIsup>(PS3″)(Cl)] (2), supported by a tris(benzenethiolato)phosphine derivative PS3″ (PS3″ = P(C<sub>6sub>H<sub>3sub>-3-Me<sub>3sub>Si-2-S)<sub>3sub><sup>3–sup>) have been synthesized and characterized. The structures resolved from X-ray crystallography show that Fe<sup>IIIsup> 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<sup>IIIsup> centers with a C<sub>3sub> symmetry (S = 3/2 ground state). The bound methoxide in 1 is labile and can be replaced by a CH<sub>3sub>CN molecule. The forming Fe<sup>IIIsup>–CH<sub>3sub>CN species can be further reduced by cobaltcene quantitatively to a stable Fe<sup>IIsup>–CH<sub>3sub>CN complex, [Fe(PS3″)(CH<sub>3sub>CN)]<sup>?sup>. One-electron oxidation of 2 by ferrocenium gave a Fe<sup>IVsup> analogue, [Fe<sup>IVsup>(PS3″)(Cl)]. Importantly, the Fe<sup>IIIsup>–OCH<sub>3sub> moiety in complex 1 acts as a strong nucleophile that activates the C–Cl bond in CH<sub>2sub>Cl<sub>2sub>, leading to the formation of complex 2 quantitatively. Complex 1 also reacts with other electrophiles, benzyl chloride and benzyl bromide, to generate Fe<sup>IIIsup>–X species (X = Cl or Br). The reactions were investigated and monitored by UV–vis–NIR, NMR, and ESI-MS spectroscopies.