Synthesis,characterization and antimicrobial studies of mixed ligand silver(I) complexes of thioureas and triphenylphosphine; crystal structure of {[Ag(PPh3)(thiourea)(NO3)]2·[Ag(PPh3)(thiourea)]2(NO3)2}

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, [(Ph₃P)₂Ag(thione)]NO₃ and [(Ph₃P)Ag(thione)₂]NO₃, 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(PPh₃)(thiourea)(NO₃)]₂·[Ag(PPh₃)(thiourea)]₂(NO₃)₂}, shows that the complex consists of two independent centrosymmetric binuclear units, each having the silver atoms coordinated to one PPh₃ 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 (Escherichiacoli, Pseudomonasaeruginosa) and molds (Aspergillusniger, Penicilliumcitrinum), while the activities were poor against yeasts (Candidaalbicans, Saccharomycescerevisiae). However, the title complex did not show activity against any tested microorganism.