Multidimensional Frameworks Assembled from Silver(I) Coordination Polymers Containing Flexible Bis(thioquinolyl) Ligands:  Role of the Intra- and Intermolecular Aromatic Stacking Interactions

The two flexible multidentate ligands 1,3-bis(8-thioquinolyl)propane (C3TQ) and 1,4-bis(8-thioquinolyl)butane (C4TQ) were reacted with AgX (X = CF3SO3- or ClO4-) to give four new complexes:  {[Ag(C3TQ)](ClO4)}n 1, {[Ag(C3TQ)](CF3SO3)}n 2, {[Ag2(C4TQ)(CF3SO3)(CH3CN)](CF3SO3)}n 3, and {[Ag(C4TQ)](ClO4)}n 4. All complexes have been characterized by elemental analysis, IR, and 1H NMR spectroscopy. Single-crystal X-ray analysis showed that chain structures form for all complexes in which the quinoline rings interact via various intra- (1) or intermolecular (2, 3, and 4) π−π aromatic stacking interactions, which in the latter cases results in multidimensional structures. Additional weak interactions, such as Ag···O and Ag···S contacts and C−H···O hydrogen bonding, are also present and help form stable, crystalline materials. It was found that the (CH2)n spacers (n = 3 or 4) affect the orientation of the two terminal quinolyl rings, thereby significantly influencing the specific framework structure that forms. If the same ligand is used, on the other hand, then the different counteranions have the greatest effect on the final structure.