A noteworthy feature in the 1A polyanion is the rather unexpected site preference between In and Zn atoms located on two atomic positions that are symmetrically unrelated but virtually identical with respect to their first coordination spheres. In the A11M6Sb12 family of structures these double pentagonal tubes are further attached to two additional MSb4 tetrahedra through lateral Sb-M bonds, and ones again in a trans-configuration. These MSb4 tetrahedra are located to the corresponding In4 positions in the idealized fully ordered 1A [Zn2In2Bi8] polyanions. The rather unexpected site preference and trans-configuration (also observed in the A11M6Sb12 family) was assigned to bonding frustration related to the peculiar electronic structure of the Pn2 dumbbells as it is characterized by a half-filled *-HOMO level. As pointed out by Bobev and co-workers, a close structural relationship exists between the 'double pentagonal tube' polyanion like [Zn2In2Bi8] 12-and the [In2Bi6] 10-polyanion with double strand structure found in Sr5In2Bi6 (Ba5Al2Bi6 type), both featuring Bi2 dumbbells, and it may help understand the unusual bonding picture of the former polyanion. If the two Zncentered tetrahedra of the double pentagonal tube [Zn2In2Bi8] 12-polyanion are suppressed, one is left with the double strands polyanion [In2Bi6] 10-(see Figure ). Thus, Bi2 dumbbells in the double pentagonal shape [Zn2In2Bi8] 12-polyanion strongly interact with two In atoms and two additionally Zn atoms in trans-configuration at longer than expected distance. Apparently, the divalent Zn atoms cannot be replaced by trivalent In atom to form hypothetical isoelectronic "[In4Bi8] 10-" polyanion, with similar double pentagonal tube structure. Thus, the 'double pentagonal tubes' motives are exclusively observed with group 12 metal based ternary pnictide. Meanwhile, the double strand structure [Tr2Pn6] 10-, like in Sr5In2Bi6 structure, have never been described with divalent group 12 element. Consequently, the title compound may be viewed as unique blend of the structural peculiarities of ternary pnictide Zintl phases with both the group 12 and 13 elements. The edge-sharing condensation mode of ZnBi4 tetrahedra is more prevalent in ternary pnictide systems with group 12 element (Zn, Cd), particularly Ba2ZnBi2. In turn, group 13 In atom are exclusively at the center of corner sharing tetrahedra, while the group 12 (Zn, Cd) atom also center edges sharing tetrahedra, and this seems to be the decisive factor for the coordination site preference between these two elements in the structure. The presence of minor amounts of In at the Zn3 sites are probably incidental doping, due to the competitive formation of the Infree ternary phase like Ba2ZnBi2 or to large In excess in the starting mixtures, and this is also in agreement with the calculated electronic band structure and total energy calculations discussed above.