Role of inorganic and organic anions in the formation of metallosupramolecular assemblies of silver(I) coordination polymers with the twisted ligand bis(4-pyridylthio)methane

Reaction of the twisted pyridyl dithioether ligand bis(4-pyridylthio)methane (4bpytm) with silver(I) salts afforded four complexes with 1:1 stoichiometries, namely [Ag(4bpytm)](NO3) (1), [Ag(4bpytm)](ClO4) (2) and [Ag(4bpytm)](ClO4) ½CH2Cl2 ½dmf (2·Solv), [Ag(CH3COO)(4bpytm)]·H2O (3) and [Ag(CF3COO)(4bpytm)] (4). X-ray structural analysis of these complexes showed that one-dimensional structures are obtained for 1, 2·Solv and 4 whereas a two-dimensional network is formed in 3. The ligand 4bpytm acts as an N,N′-bis(monodentate) bridging system in all cases except in 3, where an unprecedented coordination mode is obtained with the ligand acting in a tridentate manner using its two pyridine nitrogen atoms and a sulfur atom. The coordination polymers are assembled through secondary contacts: Ag···Ag in 4, Ag···S in 1, 2·Solv and 4, Ag···O in 2·Solv, and hydrogen bonding interactions between crystallization water that join the polymeric layers in 3. All of these weak interactions link the low-dimensional complexes to give high-dimensional supramolecular structures and further stabilize the crystal structures in the solid state.

The reaction of the twisted ligand 4bpytm with AgNO3 and AgClO4 afforded 1D cationic coordination polymers but with the carboxylate anions, CH3CO2– and CF3CO2–2D and 1D neutral coordination polymers were obtained. Different anion coordination abilities and different conformation arrangements with different symmetries and axial chirality in the ligand 4bpytm were observed in these compounds. Secondary interactions such as Ag···S, Ag···O or Ag···Ag play a crucial role in the self-organization of supramolecular polymers.Figure optionsDownload as PowerPoint slide