Synthesis and characterization of mixed-metal complexes of Ag/Cu and W/Mo and a complex of Ag with heterocyclic thione ligands

Abstract

Reactions of AgI with salts of [WS₄]²⁻ or [MoS₄]²⁻ and with either imidazolidine-2-thione (Imt) or [1,3]diazepane-2-thione (Diap) give the complexes [WS₄Ag₂(Imt)₂]_n and [MS₄Ag₂(Diap)₄] [M = W or Mo]; in the case of Diap, corresponding Cu complexes can be obtained with CuCl instead of AgI. Decomposition of the Ag–Diap complexes during attempted recrystallisation leads to the polymeric complex [AgI(Diap)]_n. The monomeric mixed-metal Diap complexes contain edge-sharing WS₄ and AgS₄ tetrahedra, the Diap ligands being terminally bonded to Ag through sulfur. The mixed-metal W–Ag–Imt complex is a chain polymer with two different environments for the WS₄ unit and three different coordination environments for Ag, one of which is an unprecedented AgS₅ square-based pyramid; Imt ligands are terminally coordinated to Ag. [AgI(Diap)]_n has a complex polymeric chain structure with three different distorted tetrahedral environments for Ag, direct Ag–Ag bonding, both bridging and terminal I, and all Diap ligands bridging pairs of Ag atoms. All the crystal structures feature N–H⋯S or N–H⋯I hydrogen bonding. The complexes have also been characterised by infrared, UV-Vis and ¹H and ¹³C NMR spectroscopy.