Switching from a chromium(IV) peroxide to a chromium(III) superoxide upon coordination of a donor in the trans position.
Switching from a chromium(IV) peroxide to a chromium(III) superoxide upon coordination of a donor in the trans position.
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DOI：
10.1021/jacs.9b06826
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发表时间：
2019-08
影响因子：
15
通讯作者：
M. Wind;S. Hoof;B. Braun‐Cula;C. Herwig;C. Limberg
中科院分区：
文献类型：
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作者：
M. Wind;S. Hoof;B. Braun‐Cula;C. Herwig;C. Limberg
在EtCN中，氧在铬(II)硅氧化物络合物上的活化导致铬(III)络合物与末端结合的超氧化物配体，而在四氢呋喃中的反应导致侧向过氧铬(IV)化合物。超氧化物与TEMPO-H(HAT)的反应速度更快，而与超氧化物不同的是，过氧化氢被证明能够使醛变形。该体系被发现代表了一种独特的情况，即使是两种结构之间的切换也可以通过溶剂实现；它在反式到O2配体的位置上的配位能力是决定性的，DFT研究支持这一点。总之，结果表明，细微的变化可以决定最初形成的金属-氧加合物是以超氧化物还是以过氧化氢的形式存在，因此值得在机理和可能的反应路线的讨论中考虑。
O2 activation at a chromium(II) siloxide complex in EtCN leads to a chromium(III) complex with an end-on bound superoxide ligand, while the reaction in THF leads to a side-on peroxo chromium(IV) compound. The superoxide reacts faster with TEMPO-H (HAT) while the peroxide, unlike the superoxide, proved capable of deformylating aldehydes. The system was found to represent a unique case, where even a switching between the two structures can be achieved via the solvent; its ability to coordinate at the position trans to the O2 ligand is decisive, as supported by DFT studies. Altogether, the results show that subtle changes can determine for an initially formed metal-dioxygen adduct, whether it exists as a superoxide or a peroxide, which thus merits consideration in discussions on mechanisms and possible reaction routes.