Hierarchy of hydrogen bonding versus anion binding in self-assembled network structures of silver(I)

Reaction of the ligands 1,2-C6H4{NHC(=O)-4-C5H4N}(2) (1) and l,2-C6H4{NHC(=O)-3-C5H4N}(2) (2) with silver(I) salts AgX, X = CF3CO2, NO3, CF3SO3, and PF6, gave the corresponding complexes [(AgX)(mu-LL)](n), 3a-4d (3a-3d: LL = 1; 4a-4d: LL = 2; a, X = CF3CO2; b, X = NO3; c, X = CF3SO3; d, X = PF6). The complexes probably exist in solution primarily as the disilver(I) macrocyclic complexes [{AgX(mu-LL)}(2)] or [Ag-2(mu-LL)(2)]X-2, but in the solid state they may exist as either macrocycles or polymers [{AgX(mu-LL)}(n)] or [Ag-n(mu-LL)(n)]X-n. The silver(I) centers have distorted tetrahedral stereochemistry when X = CF3CO2 or NO3 but roughly linear stereochemistry when X CF3SO3 or PF6, and it is argued that the hierarchy of control in the self-assembly process is by the bonds Ag-N > Ag-O > NH center dot center dot center dot O=C when X = CF3CO2 or NO3, but Ag-N > NH center dot center dot center dot O=C > Ag center dot center dot center dot O or Ag center dot center dot center dot F when X = CF3SO3 or PF6. In complexes 3a and 3b, macrocyclic complexes are connected to form polymers or sheets, respectively, through bridging anions, whereas polymers of 4a are connected through bridging anions to form a double-stranded polymer. In all these cases, network structures are formed through formation of intermolecular hydrogen bonds NH center dot center dot center dot O=C, and these porous networks contain large solvent-filled channels. In the molecular materials assembled using the more weakly bonding anions (X = CF3SO3 or PF6), the network structures are more compact, and they do not contain solvent molecules. Complexes 3e and 4d exist as polymers, whereas 4c exists as a macrocycle. These complexes are further connected through hydrogen bonding and through weak Ag center dot center dot center dot O or Ag center dot center dot center dot F interactions to form network structures. Complexes 3a-3c and 4a adopt the polar anti conformation of the two amidopyridyl units of the bidentate ligands, and 4d adopts a similar conformation with an intramolecular NH center dot center dot center dot O=C bond, but complex 4c adopts the nonpolar syn conformation. Complex 4d is unusual because it undergoes spontaneous resolution to give crystals in which chiral polymers are self-assembled to give a chiral network.