A mononuclear air-stable and water soluble six coordinated cadmium (II) complex [Cd(HL)6](ClO4)2 (1) with
bi-dentate phenol based ligand [HL = 2-(benzylimino)methyl)phenol] have been synthesized. The complex has
been characterized by various spectroscopic techniques. The solid-state structure, by single crystal X-ray
diffraction, revealed that Cd(II) complex crystallizes in trigonal space group R-3. Interestingly, single crystal Xray
structure data show that the Schiff base in the complex is present in a zwitterionic form and coordinated
through the phenolic oxygen atom only, providing the first example of more than four monodendate Schiff base
in zwitterionic form to be coordinated with the central metal ion. Cyclic voltamogram of the cadmium (II)
complex (1) exhibits a quasi-reversible oxidation peak in the positive potential region. The redox process occurs
due to the generation of phenoxyl radical from the pheolate group of the attached ligand with the central metal
ion. Luminescence spectra show a strong emission band around 500 nm. Additionally, the mononuclear cadmium
complex (1) shows catechol oxidase activity in methanol under aerobic conditions. The turnover number of the
process is 2.766 × 103 h–1. The oxidation process occurs via formation of ligand oriented phenoxyl radical
species.