Unusual changes in the intrinsic reactivity of molecules caused by non-covalent interactions

Abstract

Non-covalent interactions unavoidably lead to an electron density redistribution of the molecular systems taking part in them. Quite importantly, even if these interactions are normally weak, they significantly perturb the intrinsic reactivity of the individual systems participating in them, which usually behave as Lewis bases or as Lewis acids. The consequence is that these electron density redistributions are mirrored in dramatic changes on the intrinsic acidity or basicity of the system acting as a Lewis acid or as a Lewis base, respectively, to the point that conventional bases become very strong acids, or conventional oxyacids become very strong bases. The aforementioned changes are particularly strong when the Lewis acids participating in the interaction are electron-deficient beryllium derivatives. This electron-deficient nature is also responsible for the behavior of some specific beryllium compounds as electron and anion sponges.