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1. Fluoride Binding by a Neutral Organoantimony(V) Lewis Acid Embedded within a Dibenzodithiophene Chromophore

   https://doi.org/10.1002/zaac.202400170  

   Christianson, Anna_M; Kim, Ahran; Murphy, Brendan_L; Gabbaï, François_P (January 2025, Zeitschrift für anorganische und allgemeine Chemie)

   Organoantimony Lewis acids have been coveted for their ability to bind hard anions like fluoride in competing media. Herein, we describe the synthesis of a phenyl dithienostibole (1) in which the antimony(III) center is embedded within a planar dibenzodithiophene chromophore. Compound1reacts witho‐chloranil to form the corresponding catecholatostiborane (2); it also reacts withtert‐butyl peroxide in the presence of perfluoropinacol to form the corresponding pinacolatostiborane (3). Compound2was investigated as a platform for anion binding. UV–vis titrations in CH₂Cl₂afforded an association constant greater than 10⁷ M⁻¹pointing to the high fluoridophilicity of this new system. Density functional theory calculations highlight the role played by theσ*(Sb‐C_phenyl) orbital in imparting Lewis acidity to the antimony center of2. 

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2. 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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3. 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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4. 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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5. Activation of C−F Bonds by Electrophilic Organosilicon Sites Supported on Sulfated Zirconia

   https://doi.org/10.1002/ange.201809199  

   Culver, Damien B.; Conley, Matthew P. (October 2018, Angewandte Chemie)

   Abstract The reaction of allyltriisopropylsilane with partially dehydroxylated sulfated zirconium oxide (SZO) forms surface organosilicon species. Solid‐state NMR studies of the organosilicon functionalizedSZOshows that electrophilic [TIPS][SZO] sites are present on the surface, in addition to less reactive TIPS‐O_xand SiO_xspecies. The electrophilic [TIPS][SZO] sites are strong Lewis acids from solid‐state³¹P NMR analysis of triethylphosphine oxide (O=PEt₃) contacted materials. [TIPS][SZO] is active in hydrodefluorination reactions in the presence of Et₃SiH. 

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