Silver(I) complexes of N-methylbenzothiazole-2-thione: Synthesis, structures and antibacterial activity

Three silver(I) complexes containing N-methylbenzothiazole-2-thione (mbtt) have been prepared and structurally characterized by X-ray single-crystal analysis. Silver(I) nitrate, and silver(I) triflate react with mbtt to give homoleptic complexes of formula [(mbtt)2Ag(μ-mbtt)2Ag(mbtt)2](NO3)2 (1) and [Ag(mbtt)3](CF3SO3) (2) respectively, while silver(I) chloride gives the binuclear halide-bridged [(mbtt)2Ag(μ2-Cl)2Ag(mbtt)2] (3). In the binuclear complex 1 the two metal ions, separated by 3.73 Å from each other, are doubly bridged by the exocyclic S-atoms of two mbtt ligands, with the tetrahedral environment around each silver ion being completed by the S-atoms of two terminally bonded mbtt units. Compound 2 is mononuclear with the metal ion surrounded by the exocyclic S-atoms of three mbtt ligands in a nearly ideal trigonal planar arrangement. The new complexes showed significant in vitro antibacterial activity against certain Gram-positive and Gram-negative bacterial strains.