The activation of small molecules, such as H2, CO2, and CH4, plays an important role in heterogeneous catalysis. Recently, there is significant interest in single atom catalysis (SAC), in which atomically dispersed transition metals are used to catalyze reactions. While it is well established that the surroundings of the single atom metal site play a pivotal role in catalysis, few studies have explored the effect of spin on catalysis. To this end, the study of spin-specific reactivity of transitions metal ions in gas phase collisions provides a unique and informative means to understand SAC, particularly the influence of spin. In collaboration with experimentalists, we carried out detailed dynamics studies of such reactions using first principles based full-dimensional potential energy surfaces.1-3 It is shown that intersystem crossing between different spin states plays a key role in reactions kinetics and dynamics.

1. Liu, Y.; Ončák, M.; Meyer, J.; Ard, S. G.; Shuman, N. S.; Viggiano, A. A.; Guo, H. Intersystem crossing control of the Nb+ + CO2 → NbO+ + CO reaction. J. Phys. Chem. A 2024, 128, 6943-6953.
2. Liu, Y.; Ončák, M.; Meyer, J.; Ard, S. G.; Shuman, N. S.; Viggiano, A. A.; Guo, H. Multistate dynamics and kinetics of CO2 activation by Ta+ in the gas phase: Insights into single-atom catalysis. J. Am. Chem. Soc. 2024, 146, 14182-14193.
3. Liu, Y.; Ončák, M.; Lewis, T. W. R.; Meta, M.; Ard, S. G.; Shuman, N. S.; Meyer, J.; Viggiano, A. A.; Guo, H. Insights into facile methane activation by a spin forbidden reaction with Ta+ ions in the gas phase. Chem. Sci. 2025, 16, 5007-5016.