Frustrated LEWIS Pairs

In the chemistry of Frustrated Lewis Pairs (FLP), adduct formation between Lewis acid and base is suppressed by steric shielding and ring strain. The resulting unused reaction potential can be utilised to activate or bind small molecules. These properties allow FLPs to be used as transition-metal-free catalysts. An important example is the reduction of CO₂, which subsequently can be used as a low-cost C₁ building block.

Our group presented the first neutral geminal FLPs with tetrels as Lewis acidic components. Most of these methylene-bridged systems are able to reversibly bind CO₂ and demonstrate reactivity towards a large variety of substrates (SO₂, CS₂, NO). Furthermore, we succeeded in stabilizing highly reactive short-lived intermediates such as sulfur monoxide.

Our current efforts are focusing on extending the spectrum of Lewis acidic components to group 13 and 15 elements. The strongly differing electronic properties of the Lewis acids and the use of various bridging units allow a precise tuning of the reactivity which leads to selectivity in the formation of adducts.