A Highly Sterically Encumbered Boron Lewis Acid Enabled by a Organotellurium‐based Ligand

Lewis acidic boron compounds are ubiquitous in chemistry due to their numerous applications, yet tuning and optimizing their properties towards different purposes is still a challenging field of research. In this work, the boron Lewis acid B[OTeF3(C6F5)2]3 was synthesized by reaction of the teflate derivative HOTeF3(C6F5)2 with BCl3 or BCl3·SMe2. This new compound presents a remarkably high thermal stability up to 300 °C, as well as one of the most sterically encumbered boron centres known in the literature. Theoretical and experimental methods revealed that B[OTeF3(C6F5)2]3 exhibits a comparable Lewis acidity to that of the well‐known B(C6F5)3 and around 85% of the Lewis acidity of the related B(OTeF5)3. The affinity of B[OTeF3(C6F5)2]3 towards pyridine was accessed by Isothermal Titration Calorimetry (ITC) and compared to that of B(OTeF5)3 and B(C6F5)3. The ligand‐transfer reactivity of this new boron compound towards different fluorides was demonstrated by the formation of an anionic Au(III) complex and a hypervalent iodine(III) species.