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

Abstract

In our efforts to design discrete polynuclear metal complexes with tailored structures, four structurally related quinoline-based new monothioether ligands, 8-(2-pyridylsulfanylmethyl)quinoline (L¹), 8-(4-pyridyl- sulfanylmethyl)quinoline (L²), 8-(2-pyrimidylsulfanylmethyl)quinoline (L³), 5-methyl-2-(8-quinolylmethyl- sulfanyl)-1,3,4-thiadiazole (L⁴) have been designed, and six new Ag^I complexes with these ligands, {[AgL¹](ClO₄)(CHCl₃)}₂1, [Ag₂L¹(NO₃)₂]₂2, {[AgL¹(CH₃CN)](PF₆)}₂3, [AgL²(NO₃)]₂4, {[AgL³(CH₃OH)](ClO₄)}₂5 and {[AgL⁴](ClO₄)}₂6 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 π–π 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.