Hydrogen bonding and π–π stacking in the three-dimensional supramolecular complex bis(4,4′-bipyridinium) diaquadioxalatoferrate(II) bis(hydrogen oxalate)

Abstract

The title compound, (C(10)H(10)N(2))(2)[Fe(C(2)O(4))(2)(H(2)O)(2)](C(2)HO(4))(2), appears to be a modular associate consisting of a complex anion containing bivalent Fe as the central atom, a bridging hydrogen oxalate anion and a diprotonated 4,4-bipyridine acting as the counter-cation. The Fe(II) ion in the complex anion occupies a position on a centre of inversion. Its coordination environment is formed by six O atoms from two bidentate oxalate ligands, forming a basal plane, and two water molecules approximately perpendicular to the plane, representing a distorted octahedral geometry. These three kinds of ions are connected by strong hydrogen bonds, with donor-acceptor distances (N...O and O...O) lying in the range 2.54-2.98 A, and pi-pi stacking interactions between the 4,4'-bipyridinium cations, thus forming a three-dimensional supramolecular structure.