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

Abstract

The syntheses, structures and ligand conformations of three Cd(II) coordination polymers [Cd(L¹)(ClO₄)₂]_∞ [L¹ = N,N′-di(2-pyridyl)adipoamide], 1, {[Cd(L²)₂(CH₃OH)₂](ClO₄)₂·2CH₃OH}_∞ [L² = N,N′-di(3-pyridyl)adipoamide], 2 and [Cd(L³)₂(ClO₄)₂(CH₃CH₂OH)₂]_∞ [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 AAAtrans conformations and the L² ligands in 2 adopt GAGtrans conformations, the L³ ligands in 3 adopt AAAtrans and AGAtrans conformations. The structural types of the Cd(II) coordination polymers can be directed by ligand isomerism.