Chinese Journal of Catalysis ›› 2018, Vol. 39 ›› Issue (2): 245-249.DOI: 10.1016/S1872-2067(17)62992-9

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Chemical fixation of carbon dioxide to cyclic carbonates catalyzed by zinc(Ⅱ) complex bearing 1,2-disubstituted benzimidazole ligand

Jorge L. S. Milani, Igor S. Oliveira, Pamella A. Dos Santos, Ana K. S. M. Valdo, Felipe T. Martins, Danielle Cangussu, Rafael P. Das Chagas   

  1. Universidade Federal de Goiás, Instituto de Química, Campus Samambaia, CEP:74690-900 Goiânia, GO Brazil
  • Received:2017-10-03 Revised:2017-12-01 Online:2018-02-18 Published:2018-02-10
  • Contact: 10.1016/S1872-2067(17)62992-9
  • Supported by:

    This work was supported by Fundação de Amparo a Pesquisa do Estado de Goiás (FAPEG 201610267001033) and Programa de Pós-Graduação em Química/Instituto de Química/Universidade Federal de Goiás (PPGQ/IQ/UFG).

Abstract:

A new zinc(Ⅱ) complex of formula[ZnCl2(L1)2] (1)[L1=2-(2-thienyl)-1-(2-thienylmethyl)-1H-benzimidazole] was synthesized and fully characterized by nuclear magnetic resonance and infrared spectroscopy, elemental analysis, electrospray ionization high-resolution mass spectrometry, and thermogravimetric analysis. The molecular structure was confirmed by single-crystal X-ray diffraction. Complex 1 consists of mononuclear tetrahedral zinc(Ⅱ) units with a locked geometry resulting from weak intramolecular S…π and π-π interligand interactions. The benzimidazole ligand and its zinc(Ⅱ) complex were readily obtained through a simple synthetic route. The catalytic activity of 1 was investigated in the coupling of carbon dioxide with epoxides to produce cyclic carbonates, and a series of parameters were evaluated. The complex efficiently catalyzed the transformation of various epoxides under solvent-free conditions, with good conversions, turnover numbers, and turnover frequencies.

Key words: Carbon dioxide, Cyclic carbonate, Zinc complex, Benzimidazole ligand, Cycloaddition, Homogeneous catalysis