Laura Rodríguez (@lrraurell.bsky.social)

Electrophilicity of Anionic Iodide Ligands: Platinum(IV)-Induced Halogen Bond Donor Ability Halogen bonding (HaB) traditionally occurs between electrophilic halogen donors and nucleophilic acceptors, yet this study reveals a phenomenon wherein anionic iodide ligands demonstrate an electrophilic behavior in platinum(IV) complexes, directly contradicting their inherent nucleophilic nature. Crystallographic analysis of trans-[PtI4(CNCy)2], [PtI4(phen)]·I2, and trans-[PtI4(SMe2)2], combined with molecular electrostatic potential (ESP), quantum theory of atoms in molecules (QTAIM), natural bond orbital (NBO), and electron localization function (ELF) analyses, demonstrates that platinum(II) oxidation to platinum(IV) transforms coordinated iodides from HaB acceptors to HaB donors. This transformation occurs through positive σ-hole development at iodide ligands, with ESP values shifting from negative (−9.6 kcal/mol) in platinum(II) to positive (+1.9 kcal/mol) in platinum(IV) complexes. Energy decomposition analysis reveals that dispersion forces dominate these interactions rather than electrostatics, contrasting with classical σ-hole donors where electrostatic contributions typically prevail. Cambridge Structural Database analysis identifies 32 additional platinum(IV) structures exhibiting similar PtIV–I···Nu HaBs, demonstrating this phenomenon’s widespread nature. This study reveals new opportunities for controlling noncovalent interactions through metal oxidation state manipulation. https://pubs.acs.org/doi/full/10.1021/acs.inorgchem.5c04227