Uranium tris-aryloxide derivatives supported by triazacyclononane: Engendering a reactive uranium(III) center with a single pocket for reactivity
Uranium tris-aryloxide derivatives supported by triazacyclononane: Engendering a reactive uranium(III) center with a single pocket for reactivity
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DOI：
10.1021/ja028342n
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发表时间：
2003-04-16
影响因子：
15
通讯作者：
Meyer, K
中科院分区：
文献类型：
--
作者：
Castro-Rodriguez, I;Olsen, K;Meyer, K
报道了单核铀配合物[(ArO)(3)Tacn)U-III(NCCH3)]的合成和光谱表征。铀(III)络合物与有机叠氮化合物反应生成铀(IV)叠氮铀(V)亚胺络合物[(ArO)(3)Tacn)U-IV(N-3)]和[(ArO)(3)Tacn)U-V(NSI(CH3)(3))]。本文描述了这一类似的三氮杂环氧杂环铀三芳氧合物系列的单晶X射线衍射、光谱和计算研究。六齿、三阴离子配体以前所未有的方式与大铀离子配位，产生配位不饱和和高活性的铀中心。大环三氮杂环氧三芳氧化合物占据六个配位位置，三个芳环氧悬臂在金属中心形成一个三角平面。用密度泛函理论量子力学方法对新合成的化合物的反应活性和电子结构进行了研究。结果表明，深色铀(III)和铀(V)物种是通过pi键相互作用而稳定的，它们分别包括铀的f-轨道和轴向的乙腈和亚胺配体。相比之下，无色铀(IV)叠氮络合物中的成键本质上是纯离子的。从电子结构的角度讨论了具有[N3O_3-N-AX]核结构和氧化态+III、+IV和+V的系列配合物的磁性。
The synthesis and spectroscopic characterization of the mononuclear uranium complex [((ArO)(3)tacn)U-III(NCCH3)] is reported. The uranium(III) complex reacts with organic azides to yield uranium(IV) azido as well as uranium(V) imido complexes, [((ArO)(3)tacn)U-IV(N-3)] and [((ArO)(3)tacn)U-V(NSi(CH3)(3))]. Single-crystal X-ray diffraction, spectroscopic, and computational studies of this analogous series of uranium tris-aryloxide complexes supported by triazacyclononane are described. The hexadentate, tris-anionic ligand coordinates to the large uranium ion in unprecedented fashion, engendering coordinatively unsaturated and highly reactive uranium centers. The macrocyclic triazacyclononane tris-aryloxide derivative occupies six coordination sites, with the three aryloxide pendant arms forming a trigonal plane at the metal center. DFT quantum mechanic methods were applied to rationalize the reactivity and to elucidate the electronic structure of the newly synthesized compounds. It is shown that the deeply colored uranium(III) and uranium(V) species are stabilized via pi-bonding interaction, involving uranium f-orbitals and the axial acetonitrile and imido ligand, respectively. In contrast, the bonding in the colorless uranium(IV) azido complex is purely ionic in nature. The magnetism of the series of complexes with an [N3O3-N-ax] core structure and oxidation states +III, +IV, and +V is discussed in context of the electronic structures.