Thermally and electronically triggered hydrogen shift within a CHCH2 species via surface-assisted hydrogen tunneling

Abstract

Hydrogen shift along carbon skeletons plays a key role in isomerization and rearrangement reactions in organic synthesis and hydrocarbon catalysis. Here, we demonstrate precise control over hydrogen shift within a bistable CHCH2 species formed on a Cu(110) surface, using a single-molecule approach via scanning tunneling microscopy. Triggered either thermally or electronically, the hydrogen shift exhibits an apparent activation energy of ≈0.2 eV, which is significantly lower than that of its classical analog of 1.3 eV. In contrast, no corresponding shift is observed in the deuterated CDCD2 species, revealing a dominant quantum effect behind. This isotopic phenomenon is corroborated by deep-learning-assisted path-integral Monte Carlo simulations which identify a surface-assisted tunneling pathway. Our nanotechnological strategy does lower the activation energy barrier, enabling controllable hydrogen shift for precise molecular synthesis under milder conditions. Hydrogen shift along carbon skeletons plays a key role in isomerization and rearrangement reactions in organic synthesis and hydrocarbon catalysis, yet quantitative insights are lacking. Here, the authors observe the hydrogen shift in a pure hydrocarbon system, revealing a metal-assisted hydrogen tunneling process.