Experimental and Computational Studies of Amido Chlorogermylenes as Lewis Acids in CO2 Insertion

Abstract

A novel combination of an amido-stabilised chlorogermylene (RGeCl) and a cyclic (alkyl)(amino)carbene (cAAC) has been utilized in a frustrated Lewis pair-type reaction to activate and capture CO₂. The synthesis, characterization, and reactivity studies accompanied by extensive computational input reveal “push-pull”-type interactions in the isolated CO₂-captured compounds. Both the steric and electronic factors as well as the Lewis acidity/basicity are found to play an important role in the reactivity and ability of the FLPs to activate CO₂. The results indicate that the covalent interaction between the cAAC carbene carbon and electrophilic CO₂-carbon is too strong to facilitate further reduction or reactivity of the bound CO₂-moiety. However, the interaction between the Lewis acidic Ge-species and the nucleophilic O-atom of CO₂ shows that germylenes can be utilised as the Lewis acidic partner in FLP-type chemistry and small molecule activation.