Ligand isomerism-controlled structural diversity of cadmium(II) perchlorate coordination polymers containing dipyridyladipoamide ligands

The syntheses, structures and ligand conformations of three Cd(II) coordination polymers [Cd(L1)(ClO4)2]infinity [L1 N,N'-di(2-pyridyl)adipoamide], 1, {[Cd(L2)2(CH3OH)2](ClO4)2.2CH3OH} infinity [L2 = N,N'-di(3-pyridyl)adipoamide], 2 and [Cd(L3)2(ClO4)2(CH3CH2OH)2] N [L3 = N,N'-di(4-pyridyl) adipoamide], 3, are reported. Their structures have been characterized by X-ray crystallography. Complex 1 forms 1D zigzag chains, while complex 2 forms 2D pleated sheets which are positioned in an ABAB manner. Complex 3 shows a rare 3D entanglement from parallel polycatenation of 3-fold interpenetrated square layers. While the L1 ligands in 1 adopt AAA trans conformations and the L2 ligands in 2 adopt GAG trans conformations, the L3 ligands in 3 adopt AAA trans and AGA trans conformations. The structural types of the Cd(II) coordination polymers can be directed by ligand isomerism.