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.