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-)

Two compounds, [Ag(2,4'-bpy)]NO3 (1) and [Ae(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) Angstrom, b = 11.3981(10) Angstrom, c = 16.5299(13) Angstrom, and Z = 8, while 2 crystallizes in the monoclinic space group P2(1)/c, with a = 10.6361(4) Angstrom, b = 9.9896(4) Angstrom, c = 11.2661(6) Angstrom, beta = 98.527(4)degrees, and Z = 4. Both complexes consist of helical [Ag(2,4'-bpy)](infinity) chains that are surrounded by nitrate or perchlorate counterions. Adjacent helical chains are racemic. The Ag-1 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 Ag-1 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.