Heterocyclic-2-thione derivatives of silver(I): Synthesis, spectroscopy and structures of mono- and di-nuclear silver(I) halide complexes

Article abstract of DOI:10.1016/j.jorganchem.2013.08.020

The scarcely known chemistry of silver(I) halides with a series of heterocyclic thiones in acetonitrile (or methanol-acetonitrile) is described. Silver(I) chloride with a series of imidazolidine-2-thiones [C₃H ₅NS(N-R)] in the presence of one equivalent of PPh₃ with respect to the thione ligand has yielded chloro-bridged dinuclear complexes, [Ag₂(μ-Cl)₂(κ¹-S-C₃H ₅NS(N-R))₂(PPh₃)₂] (1, R = H; 2, R = Me; 3, R = Et), and in the presence of two equivalents of PPh₃, it has yielded mononuclear complexes, [Ag(κ¹-Cl) (κ¹-S-C₃H₅NS(N-R))(PPh₃) ₂] (4, R = Me; 5, R = Et). The n-propyl-imidazolidine-2-thione with silver(I) chloride formed only a mononuclear complex, [Ag(κ¹- Cl)(κ¹-S-C₃H₅NS(N-Prⁿ)) (PPh₃)₂] (6), in the presence of one or two equivalents of PPh₃. In contrast, silver(I) bromide with C₃H ₅NS(N-R) in the presence of one or two equivalents of PPh₃ with respect to the thione ligand has yielded bromide-bridged dinuclear complexes, [Ag₂(μ-Br)₂(κ¹-S-C ₃H₅NS(N-R))₂(PPh₃)₂] (7, R = Me; 8, R = Et; 9, R = Prⁿ). The related thio-ligands, namely, 1-methyl-imidazoline-2-thione and thiazolidine-2-thione with silver(I) bromide in the presence of one or two equivalents of PPh₃ have formed bromide bridged dimeric [Ag₂(μ-Br)₂(κ¹-S- C₃H₃NS(N-Me))₂(PPh₃)₂] (10) or mononuclear Ag(κ¹-Br)(κ¹-S-C ₃H₅NS₂)(PPh₃)₂] (11) complexes respectively. The 2,4-dithiouracil (C₄H₄N ₂S₂) with silver(I) chloride/bromide and PPh₃ has yielded hetero-bridged dinuclear complexes, [Ag₂(μ-S,S-C ₄H₃N₂S₂)(μ-X)(PPh ₃)₄] (X = Cl, 12; Br, 13) involving rupture of Ag-X bonds directly with a thio-ligand, a rare case of such rupture in metal-heterocyclic thione chemistry.