Intersystem Crossing Control of the Nb<sup>+</sup> + CO<sub>2</sub> → NbO<sup>+</sup> + CO Reaction

The\ntransfer of an oxygen atom from carbon dioxide (CO<sub>2</sub>) to\na transition metal cation in the gas phase offers atomic level\ninsights into single-atom catalysis for CO<sub>2</sub> activation.\nGiven that these reactions often involve open-shell transition metals,\nthey may proceed through intersystem crossing between different spin\nmanifolds. However, a definitive understanding of such spin-forbidden\nreaction requires dynamical calculations on multiple global potential\nenergy surfaces (PESs) coupled by spin–orbit couplings. In\nthis work, we report global PESs and spin–orbit couplings for\nthree low-lying spin (quintet, triplet, and singlet) states for the\nreaction between the niobium cation (Nb<sup>+</sup>) and CO<sub>2</sub>, which are used to investigate the nonadiabatic reaction dynamics\nand kinetics. Comparison with experimental data of kinetics and collision\ndynamics shows satisfactory agreement. This reaction is found to be\nvery similar to that between Ta<sup>+</sup> + CO<sub>2</sub>. Specifically,\nour theoretical findings suggest that the rate-limiting step in this\nreaction is intersystem crossing, rather than potential barriers.