Isolation of a Terminal Co(III)-Oxo Complex
Isolation of a Terminal Co(III)-Oxo Complex
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DOI：
10.1021/jacs.8b07399
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发表时间：
2018-10-17
影响因子：
15
通讯作者：
Anderson, John S.
中科院分区：
文献类型：
--
作者：
Goetz, McKenna K.;Hill, Ethan A.;Anderson, John S.
具有高d-电子数的后过渡金属氧代配合物作为中间体参与了许多重要的催化反应;然而，它们的反应性质往往大大限制了它们的研究。虽然这些物种的一些例子已经被分离和表征，但d-电子计数>4的络合物非常罕见。在这里，我们报告说，使用一个强有力的捐赠三（咪唑-2-亚基）硼酸盐支架能够隔离两个非常不寻常的钴III-氧代配合物，其特征在于已被彻底的一套物理技术，包括单晶X-射线衍射。这些配合物显示O原子和H原子转移反应性，并表明具有六个d-电子的末端金属氧代配合物可以显示强的金属-氧键合和足够的稳定性，使其表征。这些络合物的明确分配支持了在上述类型的催化反应中经常调用但很少观察到的相关物种的可行性。这里描述的研究改变了我们对后过渡金属氧代络合物的反应性和成键的理解，并为进一步研究这类难以捉摸的重要中间体的性质打开了大门。
Late transition metal oxo complexes with high d-electron counts have been implicated as intermediates in a wide variety of important catalytic reactions; however, their reactive nature has often significantly limited their study. While some examples of these species have been isolated and characterized, complexes with d-electron counts >4 are exceedingly rare. Here we report that use of a strongly donating tris(imidazol-2-ylidene)borate scaffold enables the isolation of two highly unusual Co-III-oxo complexes which have been thoroughly characterized by a suite of physical techniques including single crystal X-ray diffraction. These complexes display O atom and H atom transfer reactivity and demonstrate that terminal metal oxo complexes with six d-electrons can display strong metal-oxygen bonding and sufficient stability to enable their characterization. The unambiguous assignment of these complexes supports the viability of related species that are frequently invoked, but rarely observed, in the types of catalytic reactions mentioned above. The studies described here change our understanding of the reactivity and bonding in late transition metal oxo complexes and open the door to further study of the properties of this class of elusive and important intermediates.