Dataset of "Hydrogen Atom Abstraction via Hydride-Coupled Electron Transfer and Its Origin"

This study explores an alternative mechanism to canonical proton-coupled electron transfer (PCET): hydride-coupled electron transfer (HCET). HCET was identified in the reaction between a CuIII-OH complex and various organic substrates, involving hydride transfer coupled with electron transfer from CuIII-OH to the substrate in a single-barrier step. First, we identified the connection between the thermodynamic cycles and reactivity and show that the mechanism – whether HCET or PCET - is dictated by the cycle with more favorable off-diagonal thermodynamics. The distinction between the mechanisms is evidenced by correlation with electronic structure-based descriptors derived from atoms-in-molecule charges and volumes. In HCET, the hydrogen atom gains electron density and volume at transition state indicating hydride character, while in PCET, it loses electron density and volume signaling proton character. Second, intrinsic bond orbital analysis confirmed that HCET is a two-electron process (opposing to one-electron PCET): it involves the complete transfer of the proton and the C-H a-electron from substrate to the Cu ion while the b-electron undergoes a transient exchange, initially migrating to the Cu center before returning to substrate. The presented HCET mechanism is compared with the hydroxyl group transfer pathway, in which the corresponding anion/electron transfer involves three separate electrons.