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1. Tris( ortho ‐carboranyl)borane: An Isolable, Halogen‐Free, Lewis Superacid

   https://doi.org/10.1002/anie.202212073  

   Akram, Manjur O.; Tidwell, John R.; Dutton, Jason L.; Martin, Caleb D. (October 2022, Angewandte Chemie International Edition)

   Abstract The synthesis of tris(ortho‐carboranyl)borane (BoCb₃), a single site neutral Lewis superacid, in one pot from commercially available materials is achieved. The high fluoride ion affinity (FIA) confirms its classification as a Lewis superacid and the Gutmann‐Beckett method as well as adducts with Lewis bases indicate stronger Lewis acidity over the widely used fluorinated aryl boranes. The electron withdrawing effect ofortho‐carborane and lack of pi‐delocalization of the LUMO rationalize the unusually high Lewis acidity. Catalytic studies indicate that BoCb₃is a superior catalyst for promoting C−F bond functionalization reactions than tris(pentafluorophenyl)borane [B(C₆F₅)₃]. 

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2. Osme Bond: Geometric and Energetic Features in the Adducts between OsO ₄ and Lewis Bases

   https://doi.org/10.1002/chem.202304240  

   Calabrese, Miriam; Pizzi, Andrea; Daolio, Andrea; Beccaria, Roberta; Lo_Iacono, Cristina; Scheiner, Steve; Resnati, Giuseppe (February 2024, Chemistry – A European Journal)

   Abstract Adducts between OsO₄and Lewis bases exert a role in important oxidation processes such as epoxidation and dihydroxylation. It has been shown that the attractive interaction driving the formation of these adducts is a σ‐hole bond involving the metal as the electrophilic species; the term Osme Bond (OmB) was proposed for designating it. Here some new adducts between OsO₄and various bases have been characterized through single crystal x‐ray diffraction (XRD) and computational studies (density functional theory, DFT), confirming the existence of a robust correlation between σ‐hole interaction energy and deformation of the tetrahedral geometry of OsO₄. Also, some adducts formed by RuO₄with nucleophiles were investigated computationally. 

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3. Surface Modification of Black Phosphorus with Group 13 Lewis Acids for Ambient Protection and Electronic Tuning

   https://doi.org/10.1002/anie.202100308  

   Tofan, Daniel; Sakazaki, Yukako; Walz Mitra, Kendahl L.; Peng, Ruoming; Lee, Seokhyeong; Li, Mo; Velian, Alexandra (March 2021, Angewandte Chemie International Edition)

   Abstract Herein we introduce a facile, solution‐phase protocol to modify the Lewis basic surface of few‐layer black phosphorus (bP) and demonstrate its effectiveness at providing ambient stability and tuning of electronic properties. Commercially available group 13 Lewis acids that range in electrophilicity, steric bulk, and Pearson hard/soft‐ness are evaluated. The nature of the interaction between the Lewis acids and thebP lattice is investigated using a range of microscopic (optical, atomic force, scanning electron) and spectroscopic (energy dispersive, X‐ray photoelectron) methods. Al and Ga halides are most effective at preventing ambient degradation ofbP (>84 h for AlBr₃), and the resulting field‐effect transistors show excellentIVcharacteristics, photocurrent, and current stability, and are significantly p‐doped. This protocol, chemically matched tobP and compatible with device fabrication, opens a path for deterministic and persistent tuning of the electronic properties inbP. 

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4. Charge‐Separated and Lewis Paired Metal–Organic Framework for Anion Exchange and CO ₂ Chemical Fixation

   https://doi.org/10.1002/chem.202002823  

   Thapa, Sheela; Meng, Lingyao; Hettiarachchi, Eshani; Bader, Yousef_K; Dickie, Diane_A; Rubasinghege, Gayan; Ivanov, Sergei_A; Vreeland, Erika_C; Qin, Yang (October 2020, Chemistry – A European Journal)

   Abstract Charge‐separated metal–organic frameworks (MOFs) are a unique class of MOFs that can possess added properties originating from the exposed ionic species. A new charge‐separated MOF, namely, UNM‐6 synthesized from a tetrahedral borate ligand and Co²⁺cation is reported herein. UNM‐6 crystalizes into the highly symmetricP43nspace group with fourfold interpenetration, despite the stoichiometric imbalance between the B and Co atoms, which also leads to loosely bound NO₃⁻anions within the crystal structure. These NO₃⁻ions can be quantitatively exchanged with various other anions, leading to Lewis acid (Co²⁺) and Lewis base (anions) pairs within the pores and potentially cooperative catalytic activities. For example, UNM‐6‐Br, the MOF after anion exchange with Br⁻anions, displays high catalytic activity and stability in reactions of CO₂chemical fixation into cyclic carbonates. 

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5. Lewis Acidity of the SbCl ₃ / o ‐chloranil System

   https://doi.org/10.1002/anie.202505893  

   Şit, Ferit; Hunter, Nathanael_H; Maltz, Logan_T; Gabbaï, François_P (May 2025, Angewandte Chemie International Edition)

   Abstract While SbCl₃is typically inert toward oxidation byortho‐quinones, we useo‐chloranil to show that the outcome of such reactions may be altered by the presence of a donor such as triphenylphosphine oxide, which readily traps the SbCl₃(cat^Cl) synthon (cat^Cl = tetrachlorocatecholate) in the form of the corresponding adduct Ph₃PO→SbCl₃(cat^Cl). The same reaction in the presence of a chloride salt affords the corresponding antimonate anion [Cl₄Sb(cat^Cl)]⁻. Computational studies indicate that the putative SbCl₃(cat^Cl) synthon has a higher chloride ion affinity than SbCl₅, suggesting significant Lewis acidity. This property is further demonstrated by the use of the SbCl₃/o‐chloranil system for both THF polymerization and a Friedel–Crafts‐type alkylation of benzene using 1‐fluorooctane. Finally, the reaction ofE‐stilbene witho‐chloranil in the presence of SbCl₃affords the corresponding benzodioxene, suggesting that SbCl₃may also operate as a redox‐active catalyst. 

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