Ag(I) complexes containing flexible N,N′-di(2-pyridyl)adipoamide ligands:: Syntheses, structures, and ligand conformations

A new flexible ligand N,N'-di(2-pyridyl)adipoamide), LCDCl3 (1), and L center dot 2H(2)O (2), and a series of polymeric complexes of the types [AgLNO3](infinity), (3); [AgLPF6](infinity), (4); [AgLBF4CH3CN(H2O)(0.5)](infinity), (5); [AgLClO4CH3CN](infinity), (6); [AgLClO4(H2O)(0.67)](infinity), (7), and [Ag2L2.5SO4](infinity), (8), are reported. All the complexes have been structurally characterized by X-ray crystallography, confirming that complexes 3-8 are coordination polymers. The cations of 3-6 form zigzag chains, while those of 7 are helical. Complex 8 forms sinusoidal chains, which demonstrates an unusual coexistence of three ligand conformers in a coordination polymer. While L's in 1 and 2 adopt GAG trans and AAA trans conformations, respectively, all the ligands in 3-7 adopt the AAA trans conformation, and the three independent L's in 8 adopt GGG cis, AAA trans, and AGA cis conformations, respectively. These conformations also differ in the dihedral angle between the two pyridyl rings.