Coordination polymers of Ag(i) with di-Schiff base and diaminoalkanes: double helix, ladder, CdSO4 and zigzag-chain networks

Abstract

A new di-Schiff base ligand has been prepared from 3-acetylpyridine and 1,2-diaminoethane and its structure has also been characterized by single crystal X-ray diffraction. Furthermore, the ligand was found to form a 1 : 1 complex with Ag(NO₃) in CH₃CN. The crystal structure of the complex exhibits a 1D-double helix with the pitch length of 10 Å. In these reactions, the ligand was found to disintegrate into the individual components to form a crystal of a 3D-network which comprised of Ag(NO₃) and 1,2-diamino ethane. Nitrate ions occupied the channels and form several N–H⋯O hydrogen bonds with the walls of the channels. Interestingly, the topology of the 3D-network was found to be similar to that of the CdSO₄. This structure prompted us to study the reactions of Ag(NO₃) with 1,2-diaminoethane, 1,2-diaminopropane and 1,3-diaminopropane. The crystal structures of these complexes reveal that 1,2-diaminoethane forms the 3D-network similar to the above reaction, whereas 1,2-diaminopropane and 1,3-diaminopropane form a ladder and 1D-zigzag chain, respectively.