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 for in vitro antimicrobial activity against S. aureus, B. subtilis, E. coli, and C. albicans. The methoxysubstituted complex (2c) showed more promising antibacterial activity against S. aureus and B. subtilis than other compounds at the concentration tested. 1. Introduction The alkylthioalkylated anilines have found application as intermediates in production of many organic compounds [1–3] including dyes, rubber, and herbicides [4]. They act as coordinating ligands due to the presence of the aniline nitrogen and the thioether sulfur in their moiety. The hard-borderline and soft nature of the nitrogen and sulfur, respectively, in alkylthioalkylated anilines permits the formation of stable complexes between them and metal ions under mild nonextreme reacting conditions. Donor groups commonly found in many known biologically active compounds and ligands used in pharmaceutical synthesis include the nitrogen, oxygen, sulfur, and chlorine atoms. Such biopotent organic compounds with their metal complexes are being explored for their activity against a wide range of microorganisms. Sulfur-containing ligands and complexes have been explored for biological activity and practical application [5–7]. Some metal complexes of SN ligands were investigated and reported. Copper(II) complexes CuX2(N–SMe) (X = Cl, Br) obtained from alcohol solution at 0°C were not very stable [8]. Ni(II) complexes of 2-methylthiomethylaniline [8] and 8-methylthioquinoline [9] have the composition NiX2(N–SMe)2 (X = Cl, Br [8]; X = Cl, Br, I, NCS [9]). The Pd(II) and Pt(II) complexes of these ligands, on being heated in dimethylformamide were S-demethylated to yield the thiolo-bridged complexes M2Cl2(N–S)2. Complexes MX2(N–SMe) and [M(N–SMe)2](ClO4)2 (M = Pd, Pt, Cu, Hg) were derived with
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