First, clusters containing elongated trigonal prisms iso(valence)electronic with Bi6 2-are known. For instance, the elongated prism Te6 4+ was isolated in the solid state for the first time by and later by Collins et al. and Beck et al. Ziegler and collaborators investigated the electronic structure of Te6 4+ and found a weak six-center four-electron (6c-4e) transannular π*π* bonding between two {Te3} units, but no signs of aromaticity. It should be noted that elongated prisms Te6 4+ and Bi6 2-are derived by reduction of much more regular Te6 6+ and Bi6 containing in their valence shells 30 electrons distributed over six unhybridized s-type lone pairs and nine perfectly localized two-center two-electron (2c-2e) σ-bonds; same σ-bonding scheme present in non-aromatic C6H6 prismane. Particularly important for understanding stability of the prisms are the three transannular σ-bonds and the corresponding molecular orbitals (MO) presented in Figure . In regular prisms none of the transannular antibonding MOs is occupied including the φ-type lowest unoccupied molecular orbital (LUMO) a2ˈ, which in turn becomes the highest occupied MO (HOMO) upon reduction. Peerless et al. have overlooked the fact that the transannular antibonding φ-type orbital a2ˈ (HOMO) in Bi6 2-interferes with the corresponding transannular bonding orbital a1ˈ (HOMO-9) giving rise to a pair of the resonating 6p 2 lone-pairs; the remaining occupied degenerated MOs eˈ represent the delocalized 6c-4e π*-π* transannular bonding. The 6p 2 -6p 2 strong repulsion counteracts the weak 6c-4e transannular bonding and consequently Bi6 2- dissociation into two Bi3 -rings is thermodynamically favorable (ΔG° = -124.5 kJ mol -1 ), while the dissociation of the elemental Bi6 into 2Bi3• is unfavorable (ΔG° = +206.1 kJ mol -1 ). Thus, it is clear that adding two electrons to the φ-type MO introduces destabilization of the Bi6 cluster rather than aromatic stabilization.