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.