Formation of novel discrete silver(I) coordination architectures with quinoline-based monothioethers:: adjusting the intramolecular Ag•••Ag distances and complex structures by ligands modifications and variations of counter anions

In our efforts to design discrete polynuclear metal complexes with tailored structures, four structurally related quinoline-based new monothioether ligands, 8-(2-pyridylsulfanylmethyl)quinoline (L-1), 8-(4-pyridyl- sulfanyl- methyl)quinoline (L-2), 8-(2-pyrimidylsulfanylmethyl)quinoline (L-3), 5-methyl-2-(8-quinolylmethyl- sulfanyl)-1,3,4-thiadiazole (L-4) have been designed, and six new Ag-I complexes with these ligands, {[AgL1](ClO4)(CHCl3)}(2) 1, [Ag2L1(NO3)(2)](2) 2, {[AgL1(CH3CN)](PF6)}(2) 3, [AgL2(NO3)](2) 4, {[AgL3(CH3OH)](ClO4)}(2) 5 and {[AgL4](ClO4)}(2) 6 have been synthesized and characterized by single-crystal X-ray diffraction analysis. All six complexes adopt discrete structures, with 1,3,4,5 and 6 being dinuclear and 2 being tetranuclear, and Ag-Ag interactions were found to exist in complexes 1,2,3 and 6, as well as pi-pi stacking in 1-4. Furthermore, the Ag ... Ag distances in 1-6 were compared. In the six complexes, the sulfur atoms of the ligands adopt quite different coordination modes: bridging in 1,2 and 3, chelating in 5 and non-coordination in 4 and 6. In addition, the structural differences of 1,2 and 3 indicate that the change in the counter anion greatly influences the coordination modes of the ligands and the coordination geometries of Ag-I ion, which consequently affects the resulting frameworks of such complexes.