Hierarchy of Hydrogen Bonding versus Anion Binding in Self-Assembled Network Structures of Silver(I)

Reaction of the ligands 1,2-C 6 H 4 {NHC( O)-4-C 5 H 4 N} 2 ( 1 ) and 1,2-C 6 H 4 {NHC( O)-3-C 5 H 4 N} 2 ( 2 ) with silver(I) salts AgX, X = CF 3 CO 2, NO 3, CF 3 SO 3, and PF 6, gave the corresponding complexes [(AgX)(μ-LL)] n, 3a − 4d ( 3a − 3d: LL = 1; 4a − 4d: LL = 2; a, X = CF 3 CO 2; b, X = NO 3; c, X = CF 3 SO 3; d, X = PF 6 ). The complexes probably exist in solution primarily as the disilver(I) macrocyclic complexes [{AgX(μ-LL)} 2 ] or [Ag 2 (μ-LL) 2 ]X 2, but in the solid state they may exist as either macrocycles or polymers [{AgX(μ-LL)} n ] or [Ag n (μ-LL) n ]X n . The silver(I) centers have distorted tetrahedral stereochemistry when X = CF 3 CO 2 or NO 3 but roughly linear stereochemistry when X = CF 3 SO 3 or PF 6, and it is argued that the hierarchy of control in the self-assembly process is by the bonds Ag−N > Ag−O > NH···O C when X = CF 3 CO 2 or NO 3, but Ag−N > NH···O C > Ag···O or Ag···F when X = CF 3 SO 3 or PF 6 . 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···O C, and these porous networks contain large solvent-filled channels. In the molecular materials assembled using the more weakly bonding anions (X = CF 3 SO 3 or PF 6 ), the network structures are more compact, and they do not contain solvent molecules. Complexes 3c and 4d exist as polymers, whereas 4c exists as a macrocycle. These complexes are further connected through hydrogen bonding and through weak Ag···O or Ag···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···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.