Computational Examination of Transition Metal-Salen Complexes for the Reduction of CO2

In this comprehensive study, we investigated the catalytic potential of seven transition metal-salen (TM-salen) complexes for the reduction of CO2 using ab initio methods. Our findings revealed distinct catalytic behavior among the TM-salen complexes, driven by their electronic and geometric properties. The reduction of hydrogen to H2 was most favorable on Mn-salen and Cu-salen complexes, indicating potential competition with CO2 reduction. Notably, later TM-salen complexes (Co, Ni, Cu, Zn) exhibited higher energy requirements for the initial CO2 reduction, whereas Mn- and Fe-salen complexes demonstrated potential-controlled selectivity, favoring CO2 reduction beyond HCOOH at specific thresholds. Our results highlight Cr-salen and Fe-salen complexes as promising candidates for CO2RR catalysts due to their reduced competition with hydrogen reduction and low overpotentials for CO2 reduction. Furthermore, the distinct reaction profiles of TM-salen complexes offer valuable insights for the design and development of efficient catalysts for sustainable CO2 conversion and other chemical transformations. These findings provide a foundation for further exploration and optimization of TM-salen complexes as viable catalysts in environmental and energy-related applications.