Spectral characterization, molecular modeling and antimicrobial studies on hydrazone metal complexes of 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)dione and S-methyl dithiocarbazate

•A novel tridentate ONS tridentate hydrazone ligand was prepared.•The hydrazone ligand was allowed to react with a variety of metal ions.•Metal complexes have been characterized by the analytical and spectral methods.•Molecular modeling of the free ligand and its complexes has been calculated.•The antimicrobial activity of the synthesized compounds was evaluated.

Metal complexes of copper(II), nickel(II), cobalt(II), oxovanadium(IV), chromium(III) and cadmium(II) with a new bridged ONS dibasic tridentate hydrazone (H2L) derived from 5-acetyl-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione with S-methyl dithiocarbazate have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, spectral (infrared, electronic, mass, 1H NMR and ESR) studies as well as thermal gravimetric analysis (TGA). The synthesized complexes have dimeric structures with the general formula [ML(NO3)m(H2O)x]2·nH2O·zMeOH, L = dianion of the hydrazone, m = 0–1, x = 0–2, n = 0–4 and z = 0–1. The metal complexes exhibited square planar, tetrahedral and octahedral geometrical arrangements, the molar conductivity data indicates that all complexes are neutral. The Coats–Redfern equation was used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition stages of some complexes. Structural parameters of the ligand and its metal complexes have been theoretically computed on the basis of semiempirical PM3 level and the results were correlated with their experimental data. Antibacterial activities of the free ligand and its metal complexes were screened against various organisms.

Graphical abstractThione and thiol forms of the hydrazone, H2L, ligand.Figure optionsDownload full-size imageDownload as PowerPoint slide