A Mononuclear Non-Heme Manganese(IV)–Oxo Complex Binding Redox-Inactive Metal Ions

• Published in: Journal of the American Chemical Society 2013-05, Vol.135 (17), p.6388-6391
• Main Authors: Chen, Junying, Lee, Yong-Min, Davis, Katherine M, Wu, Xiujuan, Seo, Mi Sook, Cho, Kyung-Bin, Yoon, Heejung, Park, Young Jun, Fukuzumi, Shunichi, Pushkar, Yulia N, Nam, Wonwoo
• Format: Article
• Language: English
• Subjects: Electron Spin Resonance Spectroscopy; Electrons; Indicators and Reagents; Manganese - chemistry; Metals - chemistry; Models, Molecular; Molecular Conformation; Oxidation-Reduction; Oxygen - chemistry; Protons; Scandium - chemistry; Spectrometry, Mass, Electrospray Ionization; Spectrophotometry, Ultraviolet; X-Ray Diffraction
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja312113p

Redox-inactive metal ions play pivotal roles in regulating the reactivities of high-valent metal–oxo species in a variety of enzymatic and chemical reactions. A mononuclear non-heme Mn(IV)–oxo complex bearing a pentadentate N5 ligand has been synthesized and used in the synthesis of a Mn(IV)–oxo complex binding scandium ions. The Mn(IV)–oxo complexes were characterized with various spectroscopic methods. The reactivities of the Mn(IV)–oxo complex are markedly influenced by binding of Sc3+ ions in oxidation reactions, such as a ∼2200-fold increase in the rate of oxidation of thioanisole (i.e., oxygen atom transfer) but a ∼180-fold decrease in the rate of C–H bond activation of 1,4-cyclohexadiene (i.e., hydrogen atom transfer). The present results provide the first example of a non-heme Mn(IV)–oxo complex binding redox-inactive metal ions that shows a contrasting effect of the redox-inactive metal ions on the reactivities of metal–oxo species in the oxygen atom transfer and hydrogen atom transfer reactions.