Chemistry of thiocarboxylates: Synthesis and structures of neutral silver(I) thiocarboxylates with triphenylphosphine †

Abstract

The reaction of AgCl, Na+R{O}CS- (R = Me or Ph) and PPh, in the ratio 1:1:2 gave the corresponding bis-phosphine adducts, [Ag(SC{O}R)(PPh3)2] (R = Me 1 or Ph 2). The structure of 2 was shown to be a monomer by X-ray crystallography. The reactions of Na+R{O}CS- (R = Me or Ph) with mixtures of AgCl and PPh3 in the ratio 1:1:1 yielded tetrameric compounds having general formula [Ag4SC{O}R)4(PPh3)4. The solid state structure of the tetrameric triphenylphosphine silver thiocarboxylates depends on the solvents used for preparation or recrystallization. The neutral compounds [(AgPPh3)4(μ-SC{O}R)4] (R = Me 3 or Ph 5) have eight-membered Ag4S4 rings in the solid state when crystallized from CH2Cl2 solvent. In toluene 3 forms another conformational isomer, 4, with an Ag ⋯ Ag interaction of 3.1461(5) Å, whereas 5 gave compound 6 with a stepladder-like arrangement having three fused four-membered rings. The formation of conformational isomers 3 and 4 may be attributed to packing effects. The ability of the sulfur atom in PhC{O}S- ligand forming μ-S and μ3-S bridging, and that of AgI to display variable coordination geometries have aided the formation of two deformational isomers 5 and 6. The variable temperature 31P NMR of compound 1 may be interpreted in terms of a mixture of monomer and dimer in CH2Cl2 solution. The low temperature 31P NMR spectra of the other compounds were not well resolved and indicated the presence of various species present in solution due to dissociation. The structures of 3-6 have been determined by single crystal X-ray diffraction methods. © The Royal Society of Chemistry 2001.