Overview and New Insights into the Thiol Reactivity of Coordinated NO in {MNO}6/7/8 (M = Fe, Co) Complexes
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- 作者：Melody A. Rhine ; Brian C. Sanders ; Ashis K. Patra ; Todd C. Harrop
- 刊名：Inorganic Chemistry
- 出版年：2015
- 出版时间：October 5, 2015
- 年：2015
- 卷：54
- 期：19
- 页码：9351-9366
- 全文大小：810K
- ISSN：1520-510X
文摘
The reactivity of free NO (NO+, NO鈥?/sup>, and NO鈥?/sup>) with thiols (RSH) is relatively well understood, and the oxidation state of the NO moiety generally determines the outcome of the reaction. However, NO/RSH interactions are often mediated at metal centers, and the fate of these species when bound to a first-row transition metal (e.g., Fe, Co) deserves further investigation. Some metal-bound NO moieties (particularly NO+, yielding S-nitrosothiols) have been more thoroughly studied, yet the fate of these species remains highly condition-dependent and, for M鈥揘O鈥?/sup>, an unexplored field. Herein, we present an overview of thiol reactions with metal nitrosyls that result in N鈥揙 bond activation, ligand substitution on {MNO} fragments, and/or redox chemistry. We also present our results pertaining to the thiol reactivity of nonheme {FeNO}7/8 complexes [Fe(LN4pr)(NO)]鈭?0 (1 and 2) and the noncorrin {CoNO}8 complex [Co(LN4pr)(NO)] (3), an isoelectronic analogue of the {FeNO}8 complex 1. Among other products, the reaction of 1 with p-ClPhSH affords [Fe2(渭-SPh-p-Cl)2(NO)4]鈭?/sup> (anion of 6), a reduced Roussin鈥檚 red ester (rRRE), which was characterized by Fourier transform infrared (FTIR), UV鈥搗is, electron paramagnetic resonance (EPR), and X-ray diffraction. Similarly, the reaction of 1 with glutathione in buffer affords the corresponding rRRE, which has also been spectroscopically characterized by EPR and UV鈥搗is. The oxidation states of the metals and nitrosyls both contribute to the complex nature of these interactions, and as such, we discuss the varying product distribution accordingly. These studies shed insight into the products that may form through MNO/RSH interactions that lead to NOx activation and {MNO} redox.