Near-IR absorption due to supramolecular electronic interaction in an extended 3D hydrogen-bonding network material: Synthesis, crystal structure and properties of [4,4′-H < inf > 2 < /inf > bpy][Cu(mnt) < inf > 2 < /inf > ]

Abstract

The synthesis and single-crystal X-ray structure of an ion-pair complex, [4,4′-H2bpy][Cu(mnt)2] (1), is described. In the crystal structure, the interactions between anions and cations via bifurcated (bpyN)-H⋯(NC-mnt)2 hydrogen bonds give rise to a three-dimensional supramolecular network having well-defined channels. Complex 1 exhibits two redox waves at +0.44 and -0.36 V (versus SCE) in dimethylformamide corresponding to the Cu(mnt)2]1-/Cu(mnt) 2]2- and [4,4′-H2bpy] 2+/[4,4′-H2bpy]1+ couples, respectively. The near-IR absorption at 1225 nm in the solid state has been attributed to the charge transfer from the copper dithiolate anion, [Cu(mnt)2]2-, to the bipyridinium cation, [4,4 ′-H2bpy]2+. © 2004 Elsevier Ltd. All rights reserved.