Two air oxidation copper(II) complexes of salicylaldehyde derivatives obtained by in situ copper(II) ion catalysis and complexation

A new salicylaldehyde derivative 1, i.e. 5-chloro-3-(ethoxymethyl)-2-hydroxybenzaldehyde, has been prepared and structurally characterized. A novel dinuclear copper(II) complex of its air-oxidized product 2 has been successfully yielded from the in situ copper(II) ion catalysis and complexation. Additionally, another control experiment has been carried out by using 3,5-dibromo-2-hydroxybenzaldehyde as the starting material, and a similar mononuclear air oxidation copper(II) complex 3 is obtained, where 3,5-dibromo-2-hydroxybenzaldehyde has also been in situ transformed to the divalent anion of 3,5-dibromo-2-hydroxybenzoic acid.