Affecting Charges and Structures of {Bi₆} Architectures by 12‐Electron Transition Metal Fragments

Molecules based on polyatomic bismuth substructures are currently attracting a lot of attention owing to this heavy and essentially non-toxic element's uncommon chemical and physical properties, which include unprecedented bonding properties. Hexaatomic {Bi₆} substructures that underly more complex cluster structures were recently reported to adopt different structures or exhibit different structural details as a consequence of the charge of the {Bi₆} unit. This leads to either crown-shaped cycles for a nominal Bi₆ ^6- or differently distorted trigonal prisms for compositions close to Bi₆ ^2-. It was predicted by quantum chemistry that Bi₆ ^4- should adopt a distinctly distorted boat-like shape, yet a corresponding compound has remained elusive. Here, we report a proof of this assumption by the synthesis of [K(crypt-222)]₂[Bi₆{Zn(hmds)}₂] ⋅ 1.5THF (1), comprising a bimetallic [Bi₆{Zn(hmds)}₂]^2- cluster that fulfills the prediction for the geometric and electronic structure of the missing link (crypt-222=4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo-[8.8.8]hexa-cosane, hmds=hexamethyldisilazanid). A detailed quantum chemical study shows how the nature of Lewis-acidic transition metal complexes-in particular, 12-electron fragments-control and fine-tune the resulting {Bi₆} architectures in accordance with the degree of electron-withdrawal from the polybismuthide core.