Quest for ultralong C–C bonds in [1.1.1]propellane derivatives: a theoretical study

Abstract

Constructing hydrocarbons with a long C–C bond has attracted chemists for a long time. Herein, we envision the formation of an ultra-long C–C bond in [1.1.1]propellane derivatives through quantum chemical calculations. Fluorination of the wing –CH₂ group elongates the C–C distance by more than 0.1 Å compared to the parent molecule. Similarly, SiR₂ (R = H, F) substituted derivatives have much longer C–C distances of greater than 1.9 Å. The longest C–C distance reported here is 2.234 Å in the beryllium substituted derivative. Interestingly, most of the molecules have intact C–C interaction (except BH substituted one) as confirmed by detailed electronic structure analysis. Due to the toxicity related issue for Be, SiR₂ substituted [1.1.1]propellane derivatives may become viable and are expected to show an ultra-long C–C distance of greater than 1.9 Å.