Room-temperature conversion of CO2 into value-added multi-carbon products (C3 or C3+ species) remains a major challenge due to poor selectivity and limited C-C coupling pathways. Using mass spectrometry, photoelectron imaging spectroscopy, and density functional calculations, we identify the 4f-metalla-aromatic anion PrB2C2 -, which-despite lacking a C─C bond-exhibits σ and π double aromaticity involving a 4f atom. We show that PrB2C2 - reacts with CO2 at room temperature to generate C3B2O2 - with a C─C─C backbone. The C3-chain formation occurs in three stages involving two distinct C-C coupling steps enabled by flexible Pr-X bonding (X = B, C, O) and Pr-centered electron shuttling. The unique structure of PrB2C2 - directs CO2 activation toward C─C─C coupling rather than CO release. These findings deepen the understanding of f-block-mediated small-molecule activation and provide a new and tailored route for producing products with C─C bonds via CO2 conversion.
Zhang et al. (Tue,) studied this question.