Helical Silver(I)−2,4‘-Bipyridine Chains Organized into 2-D Networks by Metal−Counterion or Metal−Metal Bonding. Structures of [Ag(2,4‘-bipyridine)]X (X^- = NO₃^- or ClO₄^-)

Abstract

Two compounds, [Ag(2,4‘-bpy)]NO3 (1) and [Ag(2,4‘-bpy)]ClO4 (2), were obtained from self-assembly of AgX (X = NO3-, ClO4-) with 2,4‘-bipyridine (2,4‘-bpy). 1 crystallizes in the orthorhombic space group Pbca, with a = 11.2884(7) Å, b = 11.3981(10) Å, c = 16.5299(13) Å, and Z = 8, while 2 crystallizes in the monoclinic space group P21/c, with a = 10.6361(4) Å, b = 9.9896(4) Å, c = 11.2661(6) Å, β = 98.527(4)°, and Z = 4. Both complexes consist of helical [Ag(2,4‘-bpy)]∞ chains that are surrounded by nitrate or perchlorate counterions. Adjacent helical chains are racemic. The AgI atom is linked to two nitrogen atoms of the 2-pyridyl and 4‘-pyridyl groups from two different 2,4‘-bpy ligands as well as to the oxygen atom of the counterion. In 1, another oxygen atom of the counterion is weakly coordinated to the AgI atom of an adjacent chain, thus bridging the helical chains into a wavy 2-D network structure, whereas in 2, adjacent helical chains are linked by the weak ligand-unsupported metal−metal interactions, resulting in an open 2-D network with compressed hexagons as building units. The structures of 1 and 2 imply the role that counterions may play in the framework construction.