Template condensation of 3,5-di-tert-butyl-2-hydroxybenzaldehyde S-methylisothiosemicarbazone with pentane-2,4dione and triethyl orthoformate at elevated temperatures resulted in metal complexes of the type (ML)-L-II, where M = Ni and Cu and H2L = a novel tetradentate ligand. These complexes are relevant to the active site of the copper enzymes galactose oxidase and glyoxal oiddase. Demetalation of (NiL)-L-II with gaseous hydrogen chloride in chloroform afforded the metal-free ligand H2L. Then by the reaction of H2L with Zn(CH3COO)(2)center dot 2H(2)O in a 1:1 molar ratio in 1:2 chloroform/methanol, the complex (ZnL)-L-II(CH3OH) was prepared. The three metal complexes and the prepared ligand were characterized by spectroscopic methods (IR, UV-vis, and NMR spectroscopy), X-ray crystallography, and DFT calculations. Electrochemically generated one-electron oxidized metal complexes [NiL](+), [CuL](+), and [ZnL(CH3OH)](+) and the metal-free ligand cation radical [H2L](+center dot) were studied by EPR/UV-vis-NIR and DFT calculations. These studies demonstrated the interaction between the metal ion and the phenoxyl radical.