Identification of Oxidation State+1 in a Molecular Uranium Complex
Identification of Oxidation State+1 in a Molecular Uranium Complex
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铀分子络合物中氧化态 1 的鉴定
DOI：
10.1021/jacs.2c0651918229
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发表时间：
2022
影响因子：
15
通讯作者：
Barluzzi Luciano
中科院分区：
文献类型：
--
作者：
Barluzzi Luciano
氧化态的概念在定义元素的化学性质方面起着至关重要的作用。在元素周期表的f区中，镧系元素化合物中众所周知的氧化态包括0、+2、+3和+4，锕系元素的氧化态范围为+7至+2。氧化态+1由于其在f区元素中的缺失而明显。在这里，我们证明了铀（II）茂金属[U（η5-C5 iPr 5）2]和铀（III）茂金属[IU（η5-C5 iPr 5）2]可以在2.2.2-穴状配体存在下被钾石墨还原为铀（I）茂金属[U（η5-C5 iPr 5）2]−（1）（C5 iPr 5 =五异丙基甲基）作为[K（2.2.2-穴状配体）]+的盐。X射线晶体学研究表明1具有弯曲的茂金属结构，理论研究和磁性测量证实铀（I）的电子基态为5 f3（7s/6dz 2）1（6dx 2-y2/6dxy）1构型。1中的金属-配体键合由铀5 f、6d和7s轨道的贡献组成，其中6d轨道参与弱但不可忽略的共价相互作用。铀+1氧化态的确定扩大了f区元素可分离氧化态的范围，并可能为其他锕系元素和镧系元素提供了合成这种难以捉摸的物质的途径。
The concept of oxidation state plays a fundamentally important role in defining the chemistry of the elements. In the f block of the periodic table, well-known oxidation states in compounds of the lanthanides include 0, +2, +3 and +4, and oxidation states for the actinides range from +7 to +2. Oxidation state +1 is conspicuous by its absence from the f-block elements. Here we show that the uranium(II) metallocene [U(η5-C5iPr5)2] and the uranium(III) metallocene [IU(η5-C5iPr5)2] can be reduced by potassium graphite in the presence of 2.2.2-cryptand to the uranium(I) metallocene [U(η5-C5iPr5)2]−(1) (C5iPr5= pentaisopropylcyclopentadienyl) as the salt of [K(2.2.2-cryptand)]+. An X-ray crystallographic study revealed that1has a bent metallocene structure, and theoretical studies and magnetic measurements confirmed that the electronic ground state of uranium(I) adopts a 5f3(7s/6dz2)1(6dx2–y2/6dxy)1configuration. The metal–ligand bonding in1consists of contributions from uranium 5f, 6d, and 7s orbitals, with the 6d orbitals engaging in weak but non-negligible covalent interactions. Identification of the oxidation state +1 for uranium expands the range of isolable oxidation states for the f-block elements and potentially signposts a synthetic route to this elusive species for other actinides and the lanthanides.