A comparative study on NHC-functionalized ternary Se/Te-Fe-Cu compounds: Synthesis, catalysis, and the effect of chalcogens

Minghuey Shieh, Yu Hsin Liu, Chih Chin Wang, Si Huan Jian, Chien Nan Lin, Yen Ming Chen, Chung Yi Huang

研究成果: 雜誌貢獻文章


A novel family of N-heterocyclic carbene (NHC)-incorporated Se-Fe-Cu compounds, bis-1,3-dimethylimidazol-2-ylidene (bis-Me2-imy)-containing compound [(μ4-Se)Fe3(CO)9{Cu(Me2-imy)}2] (2), bis-N-methyl- or bis-N-isopropyl-substituted benzimidazol-2-ylidene (bis-Me2-bimy or bis-iPr2-bimy)-incorporated compounds [(μ4-Se)Fe3(CO)9{Cu(Me2-bimy)}2] (3) or [(μ4-Se)Fe3(CO)9{Cu(iPr2-bimy)}2] (4), and a bis-1,3-dimethyl-4,5-dichloroimidazol-2-ylidene (bis-Me2-Cl2-imy)-containing compound [(μ3-Se)Fe3(CO)9{Cu(Me2-Cl2-imy)}2] (5), were synthesized in moderate yields in facile one-pot reactions of the ternary pre-designed compound [(μ3-Se)Fe3(CO)9{Cu(MeCN)}2] (1) with the corresponding imidazolium salts and KOtBu in THF in an ice-water bath. Single-crystal X-ray analyses revealed that the Me2-imy compound 2 or the Me2-bimy compound 3 each exhibited a trigonal bipyramidal SeFe3(CO)9Cu geometry with an Fe2Cu plane further capped by a Cu(Me2-imy) or Cu(Me2-bimy) fragment, respectively, with one long Cu-Cu covalent bond. In addition, compound 4 also comprised a trigonal bipyramidal SeFe3(CO)9Cu core structure, but the second Cu(iPr2-bimy) group bridged the equatorial Fe-Fe edge with two unbonded Cu atoms, due to the presence of a sterically bulky iPr2-bimy fragment. On the other hand, the strong electron-withdrawing chloro-containing NHC compound 5 showed a comparatively open tetrahedral SeFe3(CO)9 metal core, where two Fe-Fe edges each were further bridged by a Cu(Me2-Cl2-imy) fragment. Due to the nonclassical C-H⋯O(carbonyl) hydrogen bonds between the CO groups of the SeFe3(CO)9Cu2 core and CH moieties of the neighboring NHC ligands, both compounds 2 and 3 comprised a one-dimensional network, while compounds 4 and 5 each were made up of a two-dimensional framework in the solid state, which efficiently enhanced the stability of these Se-Fe-Cu NHC compounds. Importantly, all of these synthesized Se-Fe-Cu NHC compounds 2-5 had pronounced catalytic activities for the homocoupling of arylboronic acids with high catalytic yields. Finally, these Se-containing Fe-Cu NHC compounds further represented excellent models for studying chalcogen effects in comparison to their Te analogs, as demonstrated by their catalytic performances and electrochemical behaviors, and by DFT calculations.

頁(從 - 到)11832-11843
期刊New Journal of Chemistry
出版狀態已發佈 - 2019 一月 1

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Materials Chemistry

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