Synthesis, reaction and structure of a highly light-stable silver(I) cluster with an Ag4S4N4 core having a tridentate N-4-morpholyl 2-acetylpyridine thiosemicarbazone ligand: Use of water-soluble silver(I) carboxylates as a silver(I) source

A novel neutral tetrameric silver(I) cluster [Ag(mtsc)](4) was obtained from reactions of a tridentate N-4-morpholyl 2-acetylpyridine thiosemicarbazone ligand (N'-[1-(2-pyridyl)ethylidene] morpholine-4-carbothiohydrazide, Hmtsc) and silver( I) sources containing Ag-O bonds (Ag2O, Ag(OAc), silver(I)2-pyrrolidone-5-carboxylate(infinity){[Ag(Hpyrrld)]2}, silver(I)5-oxo-2-tetrahydrofurancarboxylate (infinity){[Ag(othf)](2)}, and silver(I) complexes with camphanic acid (infinity){[Ag(ca)]} and (infinity){[Ag(ca)(Hca)]}). The cluster was characterized by elemental analysis, TG/DTA, FTIR and single-crystal X-ray analysis in the solid state. The solution properties of the complexes were investigated using solution molecular weight measurement, ESI-MS and solution (H-1, C-13 and P-31) NMR spectroscopy. The obtained cluster is a novel example of a light-stable Ag-I cluster with a tridentate thiosemicarbazone ligand and the second report of a crystal structure of a thiosemicarbazone silver( I) complex. The reaction of the tetramer with a large excess of PPh3 gave dimeric complexes, namely, [Ag(mu(S)-mtsc)(PPh3)](2) and [(PPh3)(2)Ag(mu(S)-mtsc)(2)Ag]. The chloroform solution of the tetrameric complex showed modest and effective activities against selected bacteria ( Bacillus subtilis, Staphylococcus aureus and Pseudomonas aeruginosa) and yeasts (Candida albicans and Saccharomyces cerevisiae), respectively, but it did not inhibit the growth of any selected microorganisms in a water-suspension system.