A novel biologically active organic ligand L (N’-benzylidenepyrazine-2-carbohydrazonamide) and its three coordination compounds have been synthesized and structurally described. Their physicochemical and biological properties have been thoroughly studied. Cu(II), Zn(II), and Cd(II) complexes have been analyzed by F-AAS spectrometry and elemental analysis. The way of metal–ligand coordination was discussed based on FTIR spectroscopy and UV-VIS-NIR spectrophotometry. The thermal behavior of investigated compounds was studied in the temperature range 25–800 °C. All compounds are stable at room temperature. The complexes decompose in several stages. Magnetic studies revealed strong antiferromagnetic interaction. Their cytotoxic activity against A549 lung cancer cells have been studied with promising results. We have also investigated the biological effect of coating studied complexes with silver nanoparticles. The morphology of the surface was studied using SEM imaging.