Heptabismuthate [Bi7I24]3–: A Main Group Element Anderson-Type Structure and Its Relationships with the Polyoxometalates

We describe the unique structural and electronic arrangement in the heptanuclear polyiodobismuthate [Bi7I24]3– which displays striking similarities with the Anderson-type structures found in polyoxometalates. This main group element anion is part of the complex [Bi­(OAc)2(thf)4]3[Bi7I24] (1) which has been characterized by X-ray crystallography. We investigated the structure, stability, and bonding of [Bi7I24]3– using relativistic dispersion-corrected density functional theory in combination with a quantitative energy decomposition and electron localization function analysis in order to better understand the main features of this isopolyanion. A comparative analysis of the properties of [Bi7I24]3– and previously reported high-nuclearity [BinX3n+m]m− anions, in the gas phase and in solution, has been performed, in the latter case to track the macroscopic solvent effects. [Bi7I24]3– is the largest building block in the class of trianionic iodobismuthates and the sole heptanuclear framework in the family of iodobismuthates.