Preparation, characterization, crystal structures and catalytic oxidation activities of two transition metal complexes of an N-heterocyclic pincer ligand

Abstract

The complexes [Co(bdpdt)(dipic)]·3H2O (1) and [Ni(bdpdt)(dipic)]·3H2O (2) (bdpdt: 2,4-bis(3,5-dimethyl-1H-pyrazol-1-yl)-6-diethylamino-1,3,5-triazine, H2dipic: 2,6-pyridinedicarboxylic acid) were synthesized by the reactions of CoCl2 or NiCl2 with bdpdt and H2dipic in mixed water–ethanol solution at 120 °C. The complexes were characterized by elemental analysis, IR spectroscopy, UV–Vis spectroscopy and single-crystal X-ray diffraction. Thermogravimetric analysis showed that both complexes are stable up to 300 °C. Structural analysis reveals that the Co(II) and Ni(II) atoms both have distorted octahedral geometries. The catalytic performances of both complexes for the oxidation by H2O2 were studied at room temperature. Two complexes containing pincer N-heterocyclic ligand and H2dipic were synthesized. All the complexes were characterized by elemental analysis, IR spectroscopy, UV–Vis spectroscopy and single-crystal X-ray diffraction. In addition, the catalytic performances of complexes 1 and 2 were also studied on the oxidation reaction of cyclohexane at room temperature.