Abstract |
A new series of half-sandwich (eta(6) -p-cymene) ruthenium(II) complexes with thiophene-2-carboxylic acid hydrazide derivatives [Ru(eta(6) -p-cymene)(Cl)(L)] [L = N -(naphthalen-1-ylmethylene)thiophene-2-carbohydrazide (L-1), N -(anthracen-9-ylmethylene)thiophene-2-carbohydrazide (L-2 ) and N -(pyren-1-ylmethylene)thiophene-2-carbohydrazide (L-3)] were synthesized. The ligand precursors and their Ru(II) complexes (1-3) were structurally characterized by spectral (IR, NMR and mass spectrometry) and elemental analysis. The molecular structures of the ruthenium(II) complexes 1-3 were determined by single-crystal X-ray diffraction. All complexes were used as catalysts for the one-pot three-component syntheses of 2,4,5-trisubstitued imidazole and 5-substituted 1H-tetrazole derivatives. The catalytic studies optimized parameters as solvent, temperature and catalyst. The catalysts revealed very active for a broad range of aromatic aldehydes presenting either electron attractor or electron donor substituents and, although less active, moderate to high activities were observed for alkyl aldehydes. |