Shi Xianghui, Deng Peng, Rajeshkumar Thayalan, Maron Laurent, Cheng Jianhua
State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry, Chinese Academy of Sciences No. 5625, Renmin Street Changchun 130022 China
School of Applied Chemistry and Engineering, University of Science and Technology of China Hefei Anhui 230026 China.
Chem Sci. 2024 Jun 20;15(30):11965-11971. doi: 10.1039/d4sc03104k. eCollection 2024 Jul 31.
Well-defined low-valent molecular rare-earth metal hydrides are rare, and limited to Yb and Eu centers. Here, we report the first example of the divalent samarium(ii) hydrido complex [(Cp)Sm(μ-H)(DABCO)] (4) (Cp = CAr, Ar = 3,5-Pr-CH; DABCO = 1,4-diazabicyclooctane) supported by a super-bulky penta-arylcyclopentadienyl ligand, resulting from the hydrogenolysis of the samarium(ii) alkyl complex [(Cp)Sm{CH(SiMe)}(DABCO)] (3). Complex 4 exhibits multi-electron redox reactivity toward a variety of substrates. Exposure of complex 4 to CO results in the formation of the trivalent samarium(iii) mixed-bis-formate/carbonate complex [(Cp)Sm(μ-η:η-OCH)(μ-η:η-CO)(μ-η:η-OCH)Sm(Cp)(DABCO)] (8), mediated by hydride insertion and reductive disproportionation reactions. Complex 4 shows four-electron reduction toward four equivalents of CS to afford the trivalent samarium(iii) bis-trithiocarbonate complex [(Cp)Sm(μ-η:η-CS)(DABCO)] (9). A mechanistic study of the formation of complex 8 was carried out using DFT calculations.
结构明确的低价态分子型稀土金属氢化物很罕见，且仅限于镱和铕中心。在此，我们报道了首例由超庞大的五芳基环戊二烯基配体支撑的二价钐（II）氢化物配合物[(Cp)Sm(μ-H)(DABCO)] (4)（Cp = CAr，Ar = 3,5-Pr-CH；DABCO = 1,4-二氮杂双环辛烷），它是由钐（II）烷基配合物[(Cp)Sm{CH(SiMe)}(DABCO)] (3) 经氢解反应生成的。配合物4对多种底物表现出多电子氧化还原反应活性。将配合物4暴露于CO中会导致形成三价钐（III）混合双甲酸酯/碳酸酯配合物[(Cp)Sm(μ-η:η-OCH)(μ-η:η-CO)(μ-η:η-OCH)Sm(Cp)(DABCO)] (8)，该反应由氢化物插入和还原歧化反应介导。配合物4对四当量的CS表现出四电子还原反应，生成三价钐（III）双三硫代碳酸酯配合物[(Cp)Sm(μ-η:η-CS)(DABCO)] (9)。利用密度泛函理论计算对配合物8的形成进行了机理研究。
