Methanolic medium was used to synthesis complexes with omeprazole using Cu(II), Zn(II), and Hg(II), however Cd(II) complex was formed in a 50:50, v/v mixture of water and methanol at ambient temperature. Corresponding metal salt and omeprazole was dissolved with minimal volume of solvent in 1:2 molar ratio separately. Solutions were combined together. Then the resulting solution was maintained at room temperature to favor the growth of the product. To maintain the pH within 10-11, dilute NaOH was poured into the mixture. The powders were separated by filtering through a filter paper. Using methanol, the sample was cleaned and dried up inside a desiccator over the blue silica gel for further use. All the complexes are found stable in air. They are insoluble in aqueous media but faintly soluble in methanolic solvent. A summerized procedure is given in Table . Free bases, omeprazole has three donor sites (two tertiary =N atom in pyridine and benzimidazole ring and one O atom in sulfinyl group) while sodium salt of these weak bases has four donor sites (two tertiary =N-atom in pyridine and benzimidazole ring, one secondary anionic -N-in benzimidazole ring and one O atom in sulfinyl group). This anionic N -is formed in solution when H + leaves the molecule. Thus these bases in alkaline medium or their sodium salts in solution provides the anionic secondary nitrogen and oxygen atom attached to the sulfinyl group (S=O)