Construction of co-ordination networks of 1,6-bis(4′-pyridyl)-2,5-diazahexane with silver(I) and copper(I). Structural diversity through change in metal ions and counter ions

Abstract

A novel flexible tetradentate ligand 1,6-bis(4′-pyridyl)-2,5-diazahexane (BPDH) was synthesized, and its coordination networks with silver(I) and copper(I) salts chracterized by X-ray single-crystal structure analysis and electrospray mass spectrometry (ES-MS). The network topologies are found to depend greatly on the counter anions and metal ions employed during the reaction and crystallization. The structure of [Ag(BPDH)]NO₃1 is a one-dimensional infinite hinged cationic chain in which the counter anions link two adjacent chains through N–H⋯O and C–H⋯O hydrogen bonds. The complex [Ag(BPDH)]ClO₄·CH₃CN 2 is a two-dimensional infinite cationic network; the solvate acetonitrile molecule and counter anions are incorporated in the channels of two adjacent sheets through C–H⋯O, N–H⋯O and N–H⋯N hydrogen bonds. The structure of [Cu(BPDH)]ClO₄3 is an infinite two-dimensional cationic grid; the counter anions are located in the voids of two layers through a single C–H⋯O hydrogen bond. The structures of the three co-ordination polymers are stabilized by face-to-face or edge-to-face π–π interactions. The results demonstrate that counter ions and transition metal ions play important roles in the formation of supramolecular frameworks.