Cationic Polyhedral Chalcogenaboranes: Activation without breaking Wade's Rules

Abstract Wade's rules are a well‐established tool for the description of the geometry of inorganic clusters. Among others, they state that a decrease or increase in charge is always accompanied by a change in the number of skeletal electron pairs (SEPs). This work reports the synthesis of the first cationic chalcogenaboranes closo ‐[12‐X‐2‐IPr‐1‐EB 11 H 10 ]BF 4 (IPr=1,3‐(2,6‐ i Pr 2 C 6 H 3 )‐imidazole‐2‐ylidene; X=H, I; E=S, Se 3 a/b , 4 a/b ) featuring the same SEP count as their neutral precursors, EB 11 H 11 , but bearing a positive charge. This ionisation significantly enhances the activity towards the electrophiles. It unlocks reactivity with very weak bases and offers the control of the regioselectivity towards hard/soft bases by the modulation of LUMO. The localisation of the positive charge within the borane cluster has been confirmed experimentally, spectroscopically and theoretically.