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-nudearity [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.