Adjusting the Frameworks of Silver(I) Complexes with New Pyridyl Thioethers by Varying the Chain Lengths of Ligand Spacers, Solvents, and Counteranions

In our efforts to systematically investigate the effects of the linker units of flexible ligands and other factors on the structures of Ag^I complexes with thioethers, five new flexible pyridyl thioether ligands, bis(2-pyridylthio)methane (L¹), 1,3-bis(2-pyridylthio)propane (L³), 1,4-bis(2-pyridylthio)butane (L⁴), 1,5-bis(2-pyridylthio)pentane (L⁵), and 1,6-bis(2-pyridylthio)hexane (L⁶), have been designed and synthesized, and the reactions of these ligands with Ag^I salts under varied conditions (varying the solvents and counteranions) lead to the formation of eight novel metal−organic coordination architectures from di- and trinuclear species to two-dimensional networks:  [Ag₃(L¹)₂(ClO₄)₂](ClO₄) (1), {[AgL³](ClO₄)}_∞ (2), {[Ag₂(L⁴)₂](ClO₄)₂(CHCl₃)}_∞ (3), {[AgL⁴](ClO₄)(C₃H₆O)}_∞ (4), {[Ag₂L⁴](NO₃)₂}_∞ (5), [Ag₂L⁴(CF₃SO₃)₂]_∞ (6), {[AgL⁵](ClO₄)(CHCl₃)}₂ (7), and {[AgL⁶](ClO₄)}_∞ (8). All the structures were established by single-crystal X-ray diffraction analysis. The coordination modes of these ligands were found to vary from N,N-bidentate to N,N,S-tridentate to N,N,S,S-tetradentate modes, while the Ag^I centers adopt two-, three-, or four-coordination geometries with different coordination environments. The structural differences of 1, 2, 3, 7, and 8 indicate that the subtle variations on the spacer units can greatly affect the coordination modes of the terminal pyridylsulfanyl groups and the coordination geometries of Ag^I ions. The structural differences of 3 and 4 indicate that solvents also have great influence on the structures of Ag^I complexes, and the differences between 3, 5, and 6 show counteranion effects in polymerization of Ag^I complexes. The influences of counterions and solvents on the frameworks of these complexes are probably based upon the flexibility of ligands and the wide coordination geometries of Ag^I ions. The results of this study indicate that the frameworks of the Ag^I complexes with pyridyl dithioethers could be adjusted by ligand modifications and variations of the complex formation conditions.