Biologically active Cr(III), Mn(III) and Fe(III) macrocyclic complexes [{M(C₃₈H₂₈N₁₂S₂)X}X₂] of Schiff base ligand (C₃₈H₂₈N₁₂S₂)obtained through the condensation of thiocarbonodihydrazide, 1 H-indol and diethyl oxalate with the molar ratio 2:2:4. The structure configurations of the newly synthesized compounds have been determined by various spectroscopic: Electronic, IR, ¹H NMR, ¹³C NMR, GCMS techniques and characterized with the help of magnetic measurements, elemental analysis, and condensation measurements. The electronic spectra of the complexes indicate a five coordinate square pyramidal geometry of the center metal ion. These compounds were tested for their antimicrobial inhibition potential against the bacteria: Staphylococcus aureus, Bacillus subtilis, Escherichiacoli, Salmonella typhi, Pseudomonasaeruginosa.and fungi Rizoctonia sp., Aspergillus sp., Penicillium sp.