Beckman Institute, California Institute of Technology, Pasadena, CA 91125.
Proc Natl Acad Sci U S A. 2012 Sep 25;109(39):15589-93. doi: 10.1073/pnas.1118329109. Epub 2012 Jul 11.
A dicobaloxime in which monomeric Co(III) units are linked by an octamethylene bis(glyoxime) catalyzes the reduction of protons from p-toluenesulfonic acid as evidenced by electrocatalytic waves at -0.4 V vs. the saturated calomel electrode (SCE) in acetonitrile solutions. Rates of hydrogen evolution were determined from catalytic current peak heights (k(app) = 1100 ± 70 M(-1) s(-1)). Electrochemical experiments reveal no significant enhancement in the rate of H(2) evolution from that of a monomeric analogue: The experimental rate law is first order in catalyst and acid consistent with previous findings for similar mononuclear cobaloximes. Our work suggests that H(2) evolution likely occurs by protonation of reductively generated Co(II)H rather than homolysis of two Co(III)H units.
一种二钴肟，其中单体 Co(III) 单元通过八亚甲基双（乙二肟）连接，通过在乙腈溶液中相对于饱和甘汞电极（SCE）为-0.4 V 的电化学催化波证明可以催化对甲苯磺酸的质子还原。通过催化电流峰高（k(app) = 1100 ± 70 M(-1) s(-1)）确定氢析出速率。电化学实验表明，H(2) 析出的速率没有显著提高，与类似单核钴肟的先前发现一致：实验速率定律在催化剂和酸方面均为一级，与类似单核钴肟的先前发现一致。我们的工作表明，H(2) 的析出可能是通过还原生成的 Co(II)H 的质子化而不是两个 Co(III)H 单元的均裂发生的。
