Ionic Cocrystals of Pharmaceutical Compounds: Sodium Complexes of Carbamazepine

Three inorganic cocrystal (ICC) forms of carbamazepine (CBZ) have been synthesized, and their crystal structures are described. [Na­(CBZ)4(MeOH)]­[I]·H2O, [Na­(CBZ)5]­[I3], and [Na­(CBZ)5]­[C13H10N]­[IBr2]2 are the first CBZ structures that contain metal cations, and the latter example also contains acridinium, which is a known metabolite of CBZ. All three Na complexes have distorted square pyramidal NaO5 coordination geometries but different conformations of the four basal ligands and different hydrogen bonding interactions for the apical ligand. The hydrogen bonded synthons that have been identified for other species that contain neutral CBZ molecules are absent in all these Na containing ICC phases and are replaced by Na–O dative bonds. However, previously identified nonpolar supramolecular constructs in the form of stacks and dimers are shared with other CBZ containing structures.