Consecutive C-C Coupling of CH₄ and CO₂ Mediated by Heteronuclear Metal Cations CuTa

The conversion of methane and carbon dioxide to form C₂ products is of great interest but presents a long-standing grand challenge due to the significant obstacle of activating the inert C-H and C═O bonds as well as forming the C-C bonds. Herein, the consecutive C-C coupling of CH₄ and CO₂ was realized by using heteronuclear metal cations CuTa⁺, and the desorption of H₂C═C═O molecules was evidenced by state-of-the-art mass spectrometry. The CuTa⁺ reaction system is significantly different from the homonuclear metal systems of Cu₂⁺ and Ta₂⁺. On the basis of density functional theory calculations, we identified that Cu can modulate the charge distribution and reduce the energy difference of crucial orbitals for the C-C coupling of CH₂ and CO units that are from the activation of CH₄ and CO₂, respectively. The crucial role of the Cu atom is of substantial importance to understand the process of the C-C coupling reaction in Cu-based heterogeneous catalytic systems. This study not only provides a promising paradigm for the design of non-noble metal species in direct conversion of CH₄ and CO₂ under mild conditions but also reveals a new molecular-level mechanism of consecutive C-C coupling for the production of H₂C═C═O, a crucial intermediate during carbonylation reactions.