Synthesis and characterization of silver(I) complexes of thioureas and thiocyanate: crystal structure of polymeric (1,3-diazinane-2-thione) thiocyanato silver(I)

Silver(I) complexes of thioureas and thiocyanate, [(Tu) AgSCN], [(Metu)AgSCN], [(Dmtu) AgSCN], [(Tmtu)(AgSCN)(1.5)], [(Imt)AgSCN], and [(Diaz) AgSCN] (where Tu = thiourea, Metu = N-methylthiourea, Dmtu = N, N'-dimethylthiourea, Tmtu = N, N, N', N'-tetramethylthiourea, Imt = 1,3-imidazolidine-2-thione, and Diaz = 1,3-diazinane-2-thione), have been prepared and characterized by elemental analysis, IR and NMR spectroscopy, and thermal analysis. The crystal structure of one of them, [(Diaz) Ag(SCN)] (1), was determined by X-ray crystallography. The crystal structure of 1 shows that the complex exists in the form of a chain-like polymer comprising [Ag(mu(2)-Diaz)(mu(2)-SCN)] units. The silver atoms are bridged by mu(2)-thione sulfur atoms of Diaz and mu(2)-thiocyanate sulfur atoms. Thereby each silver atom adopts a distorted tetrahedral coordination environment comprising four sulfur atoms, two from thione and two from thiocyanate ligands. An upfield shift in the > C=S resonance of thiones in C-13 NMR and a downfield shift in the N-H resonance in H-1 NMR are consistent with the sulfur coordination to silver(I). The appearance of a band around 2100 cm(-1) in the IR and a resonance around 125 ppm in the C-13 NMR spectrum indicates the binding of thiocyanate to silver(I).