Tribenzoatobismuth(III): A new polymorph

A new polymorph (β) was obtained for an active pharmaceutical ingredient, bis-muth tribenzoate, [Bi(C₆H₅CO ₂)₃]. The new β-polymorph is 1.05 times denser than the previously known polymorph [Rae et al. (1998). Acta Cryst. B54, 438-442]. In the β-polymorph, the Bi atom is linked with three benzoate anions, each of them acting as a bidentate ligand, and these assemblies with C₃ point symmetry can be considered as molecules. The structure of the β-polymorph has no polymeric chains, in contrast to the previously known polymorph. The molecules in the β-polymorph are stacked along [001], so that the phenyl rings of the neighbouring molecules are parallel to each other. Based on the pronounced difference in the crystal structures, one can suppose that two polymorphs should differ in the dissolution kinetics and bioavailability.