Silver(I) complexes ofN-ethylthiourea. An infrared study

Summary The following silver(I) complexes ofN-ethylthiourea, L, have been isolated in the solid state: AgLX (X = Cl, Br, ClO₄, BF₄, and CF₃CO₂), Ag₂L₃X₂ (X=ClO₄, BF₄ and CF₃CO₂), AgL₂ClO₄, AgL₃X (X = Cl, Br, I, ClO₄, BF₄ and CF₃CO₂). The decrease of the(CS) and (SCN₂) frequencies in the i.r. spectra of the complexes indicates S-coordination of the ligands. The(AgS) frequencies lie in the 267–252 cm^–1 range for terminal and 240-210 cm^–1 range for bridged or long Ag-S bonds. The following structures may be proposed for the complexes. AgLX (X = Cl and Br), polymeric trigonal coordination with bridging halide ions; Ag₂L₃A₂ (A = ClO₄ and BF₄), polymeric trigonal coordination with three bridging sulphur atoms; AgL₂ClO₄, polymeric tetrahedral coordination with four bridging sulphur atoms; AgL₃A (A = ClO₄ and BF₄), dimeric tetrahedral coordination with two terminal and two bridging sulphur atoms; AgLO₂CCF₃ and Ag₂L₃(O₂CCF₃)₂, trigonal and/or tetrahedral coordination with terminal sulphur bonds and bridging CO₂ groups; AgL₃O₂CCF₃, tetrahedral coordination with terminal sulphur bonds and a monodentate CO₂ group. In the trifluoroacetato complexes, a(AgO) band is observed at 185–209 cm^–1. The AgL₃X complexes (X = Cl, Br and I) show two(AgX) and two(AgS) bands with rather low frequencies corresponding to long metal-ligand bond distances.