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Copper(II) complexes of 2-(methylthiomethyl)anilines (1a–1f) have been obtained and characterized by elemental analyses, IR, electronic spectra, conductivity, and X-ray crystallography. The complexes (2a–2f) have the structural formula [CuCl2L] with the bidentate ligand coordinating through sulfur and nitrogen. The single crystal X-ray diffraction data reveal that the copper complex (2f) has a tetragonally distorted octahedral structure with long Cu–Cl equatorial bonds. Magnetic susceptibility measurements indicate the availability of one unpaired electron in the complexes and the conductivity measurements in DMF show their behaviour as nonelectrolytes. The solid reflectance spectra and the electronic spectra of the complexes in DMSO were determined. The ligands and their copper complexes were screened forin vitroantimicrobial activity againstS. aureus,B. subtilis,E. coli, andC. albicans. The methoxysubstituted complex (2c) showed more promising antibacterial activity againstS. aureusandB. subtilisthan other compounds at the concentration tested.

Methylthioanilines, a series of sulfur-nitrogen donor ligands substituted with OCH3, CH3, Cl, and Br, and their copper(II) complexes have been synthesized and characterized by 1H and 13C NMR, elemental analysis, FTIR, UV-Vis and EPR spectra, molar conductance, and magnetic susceptibility measurements. The NMR spectra of the ligands revealed that the para/ortho protons and para carbon were sensitive to the electronic effect of substituents. The CHNS analysis presented CuLCl2 (L = OCH3, CH3, Cl) and CuL2Cl2 (L = Br) stoichiometries for the copper complexes. FTIR spectra showed that the bidentate ligands were coordinated to the copper ion through their nitrogen and sulfur atoms. The electronic spectra have suggested square planar and octahedral geometries for these complexes. The EPR spectra demonstrated that the solid state copper(II) complexes possess dx2–y2 orbital ground state and g∥ > g⊥ > 2.0023 in a tetragonal environment. The compounds were evaluated for in vitro antimicrobial activity against S. aureus, B. subtilis, E. coli, and C. albicans. The copper complexes showed higher activity than the parent ligands against S. aureus and B. subtilis; the electron-donating OCH3 and CH3 derivatives were more active than the withdrawing Br- and Cl-substituted compounds.