Bis(4,4′-bipyridinium) di-μ-hydroxido-bis[dihydroxido(pyridine-2,6-dicarboxylato)antimonate(III,V)] octahydrate

Abstract

The reaction of antimony(III) chloride, 4,4′-bipyridine (4,4′-bipy) and pyridine-2,6-dicarboxylic acid (pydcH2), in a 1:2:2 molar ratio in an aqueous solution, resulted in the formation of the title centrosymmetric disordered mixed-valence SbIII/SbV compound, (C10H9N2)2[Sb2(C7H3NO4)2(OH)6]·8H2O or (4,4′-bipyH)2[Sb(pydc)(OH)2(μ-OH)]2·8H2O. The seven donor atoms of the (pydc)2− groups and the hydroxido ligands form a distorted pentagonal–bipyramidal arrangement around the SbIII/SbV centers. C—H...π stacking interactions between CH groups of the complex dianion and the aromatic rings of the (4,4′-bipyH)+ cations, with a distance of 2.89 Å, are observed. In the crystal structure, a wide range of noncovalent interactions, consisting of O—H...O, N—H...O and C—H...O hydrogen bonds [D...A ranging from 2.722 (2) to 3.137 (3) Å], ion pairing, π–π stacking [centroid–centroid distance of 3.4363 (13) Å] and C—H...π interactions, connect the various components into a supramolecular structure.