Search for: All records

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. 

Abstract Our interest in the design of heavy pnictogen‐based Lewis acids for anion trafficking across biological membrane mimics has led us to investigate trivalent bismuthenium cations as chloride anion transporters. Here, we describe two chlorodiarylbismuthines, elaborated on aperi‐substituted naphthalene backbone and stabilized by an adjacent thio‐ or seleno‐ether functionality that engages the bismuth center in a Ch→Bi interaction (Ch=chalcogen). These new derivatives are stable in aqueous environment and readiliy transport chloride anions across the membrane of phospholipid‐based vesicles loaded with KCl. In addition to establishing the use of such motifs in anion transport, this investigation shows that the Lewis acidity, lipophilicity, and thus chloride transport properties depend on the nature of the chalcogen. 

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. 

Abstract Our efforts in the chemistry of gold complexes featuring ambiphilic phosphine‐carbenium L/Z‐type ligand have led us to consider the reduction of the carbenium moiety as a means to modulate the gold–carbenium interaction present in these complexes. Here, it was shown that the one‐electron reduction of [(o‐Ph₂P(C₆H₄)Acr)AuCl]⁺(Acr=9‐N‐methylacridinium) produces a neutral stable radical, the structure of which showed a marked increase in the Au–Acr distance. Related structural changes were observed for the phosphine oxide analogue [(o‐Ph₂P(O)(C₆H₄)Acr]⁺, the reduction of which interfered with the P=O→carbenium interaction. These structural effects, driven by a reduction‐induced change in the electronic and electrostatic characteristics of the compounds, showed that the charge and accepting properties of the carbenium unit can be modulated. These results highlight the redox‐noninnocence of carbenium Z‐type ligand, a feature that can be exploited to induce specific conformational changes.