Synthesis and catalytic activity of ruthenium(II) complexes containing pyridine-based tridentate triamines ('NNN') and pyridine carboxylate ligands (NO)

The reaction of [(p-cymene)RuCl2](2) with K[NOa-b] (NO- = 2-picolinate, a or 2-quinaldinate, b) gave neutral [(p-cymene)RuCl(NOa-b)] (1a-b), complexes which were treated with pyridine-based meridional triamine ligands ('NNN') to create complexes of the type [RuCl(NOa-b)('NNN')] (2a: 'N = N-d, NOa(-) = 2-picolinato; 2b: 'N = N-d, NOb- = 2-quinaldinato; 3a: 'N = N-b, NOa- = 2-picolinato; 3b: 'N = N-b, NOb- = 2-quinaldinato; 4a: 'N = N-p, NOa- = 2-picolinato; 4b: 'N = N-p, NOb- = 2-quinaldinato). The new compounds were characterized by elemental analysis, IR and NMR spectroscopy and, 1b was studied by single crystal X-ray diffraction. The complexes 1-4 have been employed as catalysts for the transfer hydrogenation (TH) of acetophenone derivatives to secondary alcohols in the presence of KOH using 2-propanol as a hydrogen source at 82 degrees C. The highest catalytic activity was obtained with 3a. (C) 2012 Elsevier B. V. All rights reserved.