Syntheses and molecular structures of novel Ru(II) complexes with bidentate benzimidazole based ligands and their catalytic efficiency for oxidation of benzyl alcohol


DAYAN O., Tercan M., Özdemir N.

JOURNAL OF MOLECULAR STRUCTURE, vol.1123, pp.35-43, 2016 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 1123
  • Publication Date: 2016
  • Doi Number: 10.1016/j.molstruc.2016.06.017
  • Journal Name: JOURNAL OF MOLECULAR STRUCTURE
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.35-43

Abstract

Five bidentate ligands derived from quinoline-2-carboxylic acid, i.e. 2-(1H-benzimidazol-2-yl)quinoline (L1), 2-(1-benzyl-1H-benzimidazol-2-yl)quinoline (L2), 2-[1-(2,3,5,6-tetramethylbenzyl)-1H-benzimidazol-2-yliquinoline (L3), 2-[1-(4-chlorobenzyl)-1H-benzimidazol-2-yl]quinoline (L4), and 2-[1-(4-methylbenzyl)-1H-benzimidazol-2-yl]quinoline (L5) were synthesized. Treatment of L1-5 with [RuCl2(p-cymene)](2) and KPF6 afforded six-coordinate piano-stool Ru(II) complexes, namely, [RuCI(L1)(p-cymene)]PF6 (C1), [RuCI(L2)(p-cymene)]PF6 (C2), [RuCI(L3)(p-cymene)]PF6 (C3), [RuCI(L4)(p-cymene)] PF6 (C4), and [RuCI(L5)(p-cymene)]PF6 (C5). Synthesized compounds were characterized with different techniques such as H-1 and C-13 NMR, FT-IR, and UV-vis spectroscopy. The solid state structure of L1 and C3 was confirmed by single-crystal X-ray diffraction analysis. The single crystal structure of C3 verified coordination of L3 to the Ru(II) center. The Ru(II) center has a pseudo-octahedral three legged piano stool geometry. The complexes C1-5 were tested as catalysts for the catalytic oxidation of benzyl alcohol to benzaldehyde in the presence of periodic acid (H5IO6) (Substrate/Catalyst/Oxidant = 1/0.01/0.5). The best result was obtained with C2 (3 h -> 90%). (C) 2016 Elsevier B.V. All rights reserved.