Synthesis and characterization of the bimetallic polymers [MS4Ag2(Hmimt)2]n (where M = Mo or W,Hmimt = 1-methylimidazoline-2(3H)-thione): crystal structures of [WS4Ag2(Hmimt)2]n and [Ag2I2(Hmimt)]n

The title compounds were synthesized by the reactions of NH₄]₂MS₄] (M = Mo, W), AgI and Hmimt in acetone and characterized by IR, ¹H NMR and UV–Vis spectroscopy. The polymeric structure of WS₄Ag₂(Hmimt)₂]_n was determined by X-ray crystallography. In this compound, there are two distinctly different coordination modes for the silver atoms. One Ag atom has a pseudo-tetrahedral geometry with one terminal monodentate-S Hmimt, two μ₂-S bridging Hmimt and one S atom of a monodentate WS₄ unit. The other is surrounded by four sulfur atoms belonging in pairs to two WS₄ fragments; the coordination geometry is distorted tetrahedral. The WS₄Ag₂(Hmimt)₂]_n polymer represents the first example of tetrathiometalate anions MS₄]²⁻ (M = Mo, W, or V) coordinated to another metal atom in a monodentate fashion. In both crystal structures determined the Hmimt ligands are present in the thione form, with coordination taking place via the sulfur atom only.