Unexpected Schiff-base complex formation from the oxidation reaction of a nickel(II) complex with the meso-HMPAO ligand by molecular oxygen

The synthesis and characterization of the amine–oxime complex [Ni(meso-HMPAO)–H] · ClO4 (1) and its oxidized Schiff-base product [Ni(meso-HMPAO)-5H] · ClO4 (2), where HMPAO is hexamethyl propylene amine oxime, are presented. Complex 2 results from the oxidation of 1 by molecular oxygen in basic aqueous solution. The structural change of the amine complex 1 to the Schiff-base complex 2 was investigated by the means of NMR spectroscopy and X-ray crystallography.

The oxidation of Ni(II) complex (1) can be easily oxidized to Schiff-base Ni(II) complex (2) by molecular oxygen in water.Figure optionsDownload as PowerPoint slide