Heteroleptic ruthenium(II) complexes of 2-(2-pyridyl)benzimidazoles: A study of catalytic efficiency towards transfer hydrogenation of acetophenone

Abstract

Six ruthenium(II) complexes ([RuCl2(p-cymene)(L1–6)], SD1–6, (L1–6: bidentate pyridyl-benzimidazole ligands)) were synthesized from [RuCl2(p-cymene)]2 dimer and bidentate pyridyl-benzimidazole ligands. The compounds were characterized by elemental analysis, IR, UV–Vis, NMR and X-ray diffraction. The synthesized Ru(II) complexes (SD1–6) were tested as catalysts for the catalytic transfer hydrogenation (CTH) of acetophenone to secondary alcohols in the presence of KOH using 2-propanol as a hydrogen source at 82°C. All complexes were active catalysts for TH of acetophenone with good yields under mild conditions (after 15min, yields of up to 91%).