Supramolecular Assembly of Ag(I) Centers: Diverse Topologies Directed by Anionic Interactions

Ag(I)-Ag(I) interactions in supramolecular structures have been achieved through the use of structural support from the ligand frames. In structures involving simple ligands like pyridine, strong π-π interaction leads to spatial ordering of the individual [Ag(L)₂]⁺ units. In such structures anions also play a crucial role in dictating the final arrangement of the [Ag(L)₂]⁺ synthons. In order to determine whether the anions can solely dictate the arrangement of the [Ag(L)₂]⁺ synthons in the supramolecular structure, four Ag(I) complexes of 4-pyridylcarbinol (PyOH), namely, [Ag(PyOH)₂]X (X = NO₃^- (1), BF₄^- (2), CF₃SO₃^- (3), and ClO₄^- (4)) have been synthesized and structurally characterized. Gradual transformation of the extended structures observed in 1-3 eventually merges into a unique linear alignment of the [Ag(PyOH)₂]⁺ units in 4 along the c axis, a feature that results in strong argentophilic interactions. Complex 4 is sensitive to light and is inherently less stable than the other three analogues. The structural variations in this set of extended assemblies are solely dictated by the anions, since π-π interaction between the substituted pyridine ligands is significantly diminished due to disposition of the -CH₂OH substituent at the 4 position and H-bonding throughout the structure.