The asymmetric unit of title compound, (C13H30N3)3[Bi3I12], comprises one cation and two independent (1/6) fragments of the [Bi3I12]3− ions. The C—N bond lengths in the guanidinium ion range from 1.340 (4) to 1.345 (4) Å, indicating partial double-bond character pointing towards charge delocalization within the NCN planes. The BiIII ions are distorted octahedrally coordinated by six iodide ions, with Bi—I bond lengths ranging from 2.9206 (3) to 3.3507 (3) Å. Three [BiI6]3− octahedra are fused together through face-sharing, forming a trinuclear [Bi3I12]3− unit.
