Polybismuthide Anions as Ligands: The Homoleptic Complex [(Bi₇ )Cd(Bi₇ )]^4- and the Ternary Cluster [(Bi₆ )Zn₃ (TlBi₅...

We present the results from a reactivity study of the binary anion (TlBi₃ )^2- towards Group 12 metal compounds MPh₂ (M=Zn, Cd, Hg) to gain access to coordination compounds of polycyclic polypnictide molecules such as Bi₇ ^3- or Bi₁₁ ^3- . The coordination chemistry of these polybismuthide cages has been unprecedented to date, while it has been known for a long time for the lighter Group 15 anions Pn₇ ^3- (Pn=P, As, Sb). The use of (TlBi₃ )^2- , previously shown to release Tl under certain conditions in situ, resulted in the formation of the first heterometallic polyanion in which a nortricyclane-type polybismuthide coordinates a transition-metal atom, [(Bi₇ )Cd(Bi₇ )]^4- . Reactions with the lighter Group 12 metal precursor yielded the uncommon ternary cluster [(Bi₆ )Zn₃ (TlBi₅ )]^4- , most likely representing a reaction intermediate, and at the same time hinting at the formation of the nortricyclane-shaped cage. Quantum-chemical studies provide deeper insight into the stability trends of the [(E₇ )M(E₇ )]^4- anion family and reveal a complex bonding situation in [(Bi₆ )Zn₃ (TlBi₅ )]^4- , which features both localized and multi-center bonding.