Department of Bioinspired Science, Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.
J Am Chem Soc. 2013 May 1;135(17):6388-91. doi: 10.1021/ja312113p. Epub 2013 Jan 23.
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 Sc(3+) 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.
氧化还原惰性金属离子在各种酶促和化学反应中调节高价金属氧物种的反应性方面发挥着关键作用。本文报道了一种单核非血红素 Mn(IV)-氧配合物，该配合物具有五齿 N5 配体，用于合成结合钪离子的 Mn(IV)-氧配合物。通过各种光谱方法对 Mn(IV)-氧配合物进行了表征。在氧化反应中，Mn(IV)-氧配合物的反应性明显受到 Sc(3+)离子结合的影响，例如硫代茴香醚（即氧原子转移）的氧化速率增加了约 2200 倍，但 1,4-环己二烯（即氢原子转移）的 C-H 键活化速率降低了约 180 倍。本研究结果提供了首例结合氧化还原惰性金属离子的非血红素 Mn(IV)-氧配合物的实例，表明氧化还原惰性金属离子对氧原子转移和氢原子转移反应中金属氧物种反应性的影响相反。
