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

The reaction of AgCl, Na+R{O}CS- (R = Me or Ph) and PPh3 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 [Ag-4(SC{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)(mu -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) Angstrom, 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 mu -S and mu (3)-S bridging, and that of Ag-I to display variable coordination geometries have aided the formation of two deformational isomers 5 and 6. The variable temperature P-31 NMR of compound 1 may be interpreted in terms of a mixture of monomer and dimer in CH2Cl2 solution. The low temperature P-31 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.