Acta Chimica Sinica ›› 2020, Vol. 78 ›› Issue (10): 1096-1101.DOI: 10.6023/A20070284 Previous Articles     Next Articles



杨之策, 田佳楠, 才洪雪, 李丽, 潘清江   

  1. 黑龙江大学功能无机材料化学教育部重点实验室 化学化工与材料学院 哈尔滨 150080
  • 投稿日期:2020-07-02 发布日期:2020-08-05
  • 通讯作者: 潘清江
  • 基金资助:

Theoretical Probe for Tris(aryloxide)arene Complexed Low-valent Actinide Ions and Their Structural/Redox Properties

Yang Zhice, Tian Jianan, Cai Hongxue, Li Li, Pan Qingjiang   

  1. Key Laboratory of Functional Inorganic Material Chemistry of Education Ministry, School of Chemistry and Materials Science, Heilongjiang University, Harbin 150080, China
  • Received:2020-07-02 Published:2020-08-05
  • Supported by:
    Project supported by the National Natural Science Foundation of China (No. 21671060), the Natural Science Foundation of Heilongjiang Province (No. LH2019B029) and the Heilongjiang Touyan Innovation Team Program.

It is of great significance to identify new oxidation state of actinide, which will enrich actinide coordination chemistry and advance its exploration of chemical bond and reactivity. So far, uranium with +3~+6 oxidation states has been widely recognized in complexes. Comparatively, isolated, crystallographically identified U(II) complexes remain rare. Inspired by the pioneering work of Evans and co-workers that Y·[UII(Cp')3] (Y=[K(2.2.2-cryptand)]+, Cp'=[C5H4SiMe3]-) was structurally characterized, several uranium(II) complexes such as Y·[ULE] (LE=[(Ad,MeArO)3 mesitylene]3-, Ad=adamantyl),[U(NHAriPr6)2] (AriPr6=2,6-(2,4,6-iPr3C6H2)2C6H3), Y·[U{N(SiMe3)2}3] and[U(η5-C5iPr5)2] were synthetically accessible. Inspection finds that all these U(II) complexes were prepared in the same route, i.e., utilizing potassium graphite or potassium sphere to reduce respective U(III) parent at low temperature. Cyclopentadiene (Cp) and arene (Ar)-based ligands are involved. They are key to determine U(II) electron configuration, leading to 5f36d1 and 5f4, respectively. Moreover, δ(U-Ar) bonds play a significant role in stabilizing arene-ligated complexes. With the supporting of Cp-derived ligands, actinide(II) complexes were extended to Th, Np and Pu. Unfortunately, it is not the case for the arene ligands, even with massive efforts. Given the prevailing route that actinide(II) complex was synthesized by reducing its trivalent parent, the exploration of redox property will help to guide the synthesis of more novel U(II) and even other actinide(II) complexes. In this respect, theoretical computation based on accurate methodology is greatly appealing. Herein, relativistic density functional theory was exploited to investigate structural and redox properties of[AnL]z (An=Ac~Pu; L=[(Me,MeArOH)3Ar]3-; z=0 and -1), where analogues of uranium complexes were experimentally known. It is found that the central arene moiety is redox-active for Ac and Th complexes in the reduction reaction, while the metal center is reduced for other complexes. So Ac and Th in reduced products still remain +3 oxidation states, whereas metals in others turn +2. The 5fn electronic configuration is unraveled for actinide of[AnL]- (An=Pa~Pu), having 3~6 electrons, respectively. Calculated redox potential (E0) increases from Ac to Pu in general, where U and Np show lower values than adjacent elements. A good correlation has been built between E0 and Δ(An-CAr/An-Arcent)/electron affinity. In brief, the study is expected to provide theoretical support for the synthesis of novel arene-based actinide(II) complexes.

Key words: δ(An-Ar)-type low-valent actinide complexes, tris(aryloxide)arene, electronic structure, redox reaction, relativistic density functional theory