{Fe(NO)2}9 Dinitrosyl Iron Complex Acting as a Vehicle for the NO Radical

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• 作者：Chun-Hung Ke ; Chien-Hong Chen ; Ming-Li Tsai ; Hsuan-Chi Wang ; Fu-Te Tsai ; Yun-Wei ChiangWei-Chih Shih ; D. Scott Bohle ; Wen-Feng Liaw
• 刊名：Journal of the American Chemical Society
• 出版年：2017
• 出版时间：January 11, 2017
• 年：2017
• 卷：139
• 期：1
• 页码：67-70
• 全文大小：334K
• ISSN：1520-5126

文摘

To carry and deliver nitric oxide with a controlled redox state and rate is crucial for its pharmaceutical/medicinal applications. In this study, the capability of cationic {Fe(NO)<sub>2sub>}<sup>9sup> dinitrosyl iron complexes (DNICs) [(<sup>Rsup>DDB)Fe(NO)<sub>2sub>]<sup>+sup> (R = Me, Et, Iso; <sup>Rsup>DDB = N,N′-bis(2,6-dialkylphenyl)-1,4-diaza-2,3-dimethyl-1,3-butadiene) carrying nearly unperturbed nitric oxide radical to form [(<sup>Rsup>DDB)Fe(NO)<sub>2sub>(<sup>•sup>NO)]<sup>+sup> was demonstrated and characterized by IR, UV–vis, EPR, NMR, and single-crystal X-ray diffractions. The unique triplet ground state of [(<sup>Rsup>DDB)Fe(NO)<sub>2sub>(<sup>•sup>NO)]<sup>+sup> results from the ferromagnetic coupling between two strictly orthogonal orbitals, one from Fe d<sub>z<sup>2sup>sub> and the other a π*<sub>opsub> orbital of a unique bent axial NO ligand, which is responsible for the growth of a half-field transition (ΔM<sub>Ssub> = 2) from 70 to 4 K in variable-temperature EPR measurements. Consistent with the NO radical character of coordinated axial NO ligand in complex [(<sup>Mesup>DDB)Fe(NO)<sub>2sub>(<sup>•sup>NO)]<sup>+sup>, the simple addition of MeCN/H<sub>2sub>O into CH<sub>2sub>Cl<sub>2sub> solution of complexes [(<sup>Rsup>DDB)Fe(NO)<sub>2sub>(<sup>•sup>NO)]<sup>+sup> at 25 °C released NO as a neutral radical, as demonstrated by the formation of [S<sub>5sub>Fe(NO)<sub>2sub>]<sup>−sup> from [S<sub>5sub>Fe(μ-S)<sub>2sub>FeS<sub>5sub>]<sup>2–sup>.