Diiron hexacarbonyl complexes as potential CO-RMs: CO-releasing initiated by a substitution reaction with cysteamine and structural correlation to the bridging linkage.
Diiron hexacarbonyl complexes as potential CO-RMs: CO-releasing initiated by a substitution reaction with cysteamine and structural correlation to the bridging linkage.
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DOI：
10.1039/c3dt53620c
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发表时间：
2014-06
影响因子：
4
通讯作者：
Xiujuan Jiang;Li Long;Hailong Wang;Limei Chen;Xiaoming Liu
中科院分区：
文献类型：
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作者：
Xiujuan Jiang;Li Long;Hailong Wang;Limei Chen;Xiaoming Liu
通过半胱胺（CysA）的取代反应，研究了9种双铁羰基配合物（）的CO释放行为。这些配合物分为三类，由两个硫醇盐，一个二硫醇盐和1，8-萘二硫醇盐桥接的二铁核心。我们的研究结果表明，这些配合物的CO释放速率是高度依赖于它们的结构。具有两个单硫醇盐作为其桥键的络合物（）（“开放”形式）与具有二硫醇盐作为其桥键的络合物（）相比，在亲核取代反应时更容易分解。当桥连键缺乏给电子基团（络合物）时，金属中心带的负电荷较少，如DFT计算所揭示的，因此它表现出与CysA的快速取代反应以释放CO。具有共轭性质的键（）表现出类似的效果，因为金属中心上的电子密度由于电子密度从金属中心转移到萘部分而降低。动力学分析表明，CO的释放在这些复合物的第一阶段是一个一级反应。
The CO-releasing behaviours of nine diiron carbonyl complexes () were examined via the substitution reaction of cysteamine (CysA), of which complex was reported recently. These complexes fall into three categories, the diiron core bridged by two thiolates, a dithiolate and 1,8-naphthalene dithiolate. Our results reveal that the CO-releasing rates of these complexes are highly dependent on their structures. Complexes () bearing two monothiolates as their bridging linkage ("open" form) are more vulnerable to decomposition upon nucleophilic substitution reactions compared with complexes () that possess a dithiolate as their bridging linkage. When the bridging linkage lacks an electron-donating group (complex ), the metal centre is less negatively charged as revealed by DFT calculation, and thus it exhibits fast substitution reaction with CysA to release CO. A linkage with conjugating nature () shows a similar effect because electron density on the metal centre decreases due to electron-density diverting from the metal centre into the naphthalene moiety. Kinetic analysis suggests that CO-releasing at the first stage of these complexes is a first-order reaction.