Rethinking polyiodides: the role of electron-deficient multicenter bonds

• Published in: Chemical communications (Cambridge, England) England), 2024-10, Vol.6 (87), p.12677-12689
• Main Authors: Savastano, Matteo, Osman, Hussien H, Vegas, Ángel, Manjón, Francisco Javier
• Format: Article
• Language: English
• Subjects: Chemical bonds; Covalent bonds; Polyelectrolytes
• ISSN: 1359-7345; 1364-548X; 1364-548X
• DOI: 10.1039/d4cc02832e

Despite a bicentennial history, the interest in polyiodides and related systems still flourishes. The chemical puzzle provided by the intricate nature of chemical bonding in these polyanions remains challenging these days. The advent of the halogen bond and the spreading interest in supramolecular interactions of halogen-based systems promoted further recent interest. Research in the area of materials, where local bonding details eventually result in desired macroscopic properties, provided a further boost. Herein, we illustrate the consequences of contemplating a different bonding scheme for polyiodides, one making explicit use of electron-deficient multicenter bonds (EDMBs), an emerging concept in this area. We present a reinterpretation of polyiodide bonding using a revised approach to the Lewis dot formulas, leading to a clearer pen-and-paper understanding of their bonding. The model is general and can be applied to other related problems (here polyiodonium cations, and other homo- and hetero-polyhalides). Our alternative narrative has a few interesting consequences on several traditional and currently hot topics, including the nature of basic building blocks for polyiodides, hypervalency vs. hypercoordination, the distinction between covalent bonds and supramolecular interactions, and the nature of secondary and halogen bonds. We summarize progresses in understanding the nature of bonding in polyiodides, showing the need of including electron-deficient multicenter bonds in their description. A revision of Lewis dot formulas allows to simply depict and rethink the matter.