Synthesis and characterization of novel transition metal complexes with indole acetic acid ligands: Evaluation of their catalytic activity for the oxidation of cyclohexane

Two new transition metal complexes Co(IAA)2(phen)(H2O) (1) and Ni(IAA)2(phen)(H2O) (2) (IAA = indole acetic acid, phen = 1,10-phenanthroline) with IAA and phen as mixed ligands are synthesized and characterized by elemental analysis, IR spectra, UV–Vis spectroscopy and single-crystal X-ray diffraction. The structural analysis shows that the coordination mode of the ligand IAA in complexes 1 and 2 were similar: the former is in a μ1–η1 linking fashion, while the latter is in a μ1–η1–η1 linking fashion. In addition, the thermogravimetric analysis of the complexes was investigated in detail. The catalytic activity of the two complexes has been invested in the oxidation of cyclohexane with the presence of H2O2 as primary oxidant under mild conditions, which shows that cobalt complex with IAA ligand exhibited a good catalytic activity with the maximum TON value of 110.