Bis(2-(1H-imidazol-2-yl)-pyridine)copper(II): Effects of counteranions on the molecular and supramolecular structures

The synthesis and physical properties of bis(2-(1H-imidazol-2-yl)-pyridine)copper(11) with chloride, nitrate and perchlorate as counteranions have been described. Microanalysis, magnetic susceptibility, conductivity and various spectroscopic measurements have been used for the characterization of the complexes. The crystal structures of all three complexes have been determined. Intermolecular hydrogen-bonding interactions and the resulting self-assembly patterns for each of the species have been scrutinized. The chloride containing complex crystallizes as a trihydrate, where the metal ion is in a tetragonally elongated cis-N4Cl2 coordination sphere. This complex provides a three-dimensional honeycomb-like structure through N-H center dot center dot center dot Cl, O-H center dot center dot center dot Cl and O-H center dot center dot center dot O hydrogen bonds. In the nitrate containing species, one of the two counteranions coordinates to the metal centre to provide an irregular N4O2 coordination sphere, while the other counteranion, with the help of a lattice water molecule, assembles a ladder-like structure via N-H center dot center dot center dot O and bifurcated O-H center dot center dot center dot O,O hydrogen bonds. A one-dimensional polymeric species has been formed when perchlorate is the counteranion. Here one of the two perchlorates acts as a bridge between the metal centres that are in tetragonally elongated trans-N4O2 coordination spheres. This polymeric chain, together with the second perchlorate and a water molecule, form a ribbon-like structure due to N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen bonds. (C) 2010 Elsevier Ltd. All rights reserved.