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

Abstract

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(μ 2 -Diaz)(μ 2 -SCN)] units. The silver atoms are bridged by μ 2 -thione sulfur atoms of Diaz and μ 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 13 C NMR and a downfield shift in the N-H resonance in 1 H 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 13 C NMR spectrum indicates the binding of thiocyanate to silver(I).