Ortho-Carborane-Derived Halogen Bonding Organocatalysts

Abstract

Multidentate neutral halogen bonding catalysts based on iodinated icosahedral ortho-carborane moieties are introduced. Co-crystallization-studies, calorimetric measurements, and 1H NMR titrations demonstrate their strong binding to halides and neutral compounds, further underlined by quantum-chemical calculations. Thus, their superior Lewis acidity compared to traditional perfluorinated halogen-bond donors has been shown. The iodocarborane catalysts also outperformed the latter in a halide abstraction reaction and catalyzed a nitro-Michael addition reaction, which was previously out of reach for neutral halogen-bonding-based organocatalysts.