Synthesis, characterization and antimicrobial studies of mixed ligand silver(I) complexes of thioureas and triphenylphosphine; crystal structure of {[Ag(PPh 3)(thiourea)(NO 3)] 2·[Ag(PPh 3)(thiourea)] 2(NO 3) 2}

Abstract

Mixed ligand silver(I) complexes of triphenylphosphine and thioureas (thiourea (Tu), N-methylthiourea (Metu), N, N′-dimethylthiourea (Dmtu) and N, N′-diethylthiourea (Detu)) with the general formulae, [(Ph 3P) 2Ag(thione)]NO 3 and [(Ph 3P)Ag(thione) 2]NO 3, have been prepared and characterized by elemental analysis, IR and NMR ( 1H, 13C and 31P) spectroscopic methods. The crystal structure of one of them has been determined by X-ray crystallography. The spectral data of the complexes are consistent with sulfur coordination of the thiones to silver(I). The single crystal X-ray structure of complex 1, {[Ag(PPh 3)(thiourea)(NO 3)] 2·[Ag(PPh 3)(thiourea)] 2(NO 3) 2}, shows that the complex consists of two independent centrosymmetric binuclear units, each having the silver atoms coordinated to one PPh 3 and two bridging thiourea molecules. In one of the independent units the silver atom is additionally bound to a nitrate ion, leading to a tetrahedral geometry, while in the other unit the silver atom adopts a trigonal planar environment. Antimicrobial activities of the complexes were evaluated by their minimum inhibitory concentration and the results showed that the complexes show a wide range of activity against two gram-negative bacteria ( Escherichia coli, Pseudomonas aeruginosa) and molds ( Aspergillus niger, Penicillium citrinum), while the activities were poor against yeasts ( Candida albicans, Saccharomyces cerevisiae). However, the title complex did not show activity against any tested microorganism.