Isolation and identification of surface-bound acetone enolate on Ni(111)

A surface-bound acetone enolate species has been synthesized on Ni(111) between 260 and 340 K by two different routes catalyzed by surface Ni and O atoms: deprotonation of acetone and deacetylation of acetylacetone. The reaction pathways and surface species have been identified using reflection absorption infrared spectroscopy (RAIRS) in combination with isotopic substitution and density functional theory (DFT) calculations. Acetone enolate exhibits characteristic vibrational absorption bands at 1260, 1353, and 1545 cm-1 arising from mixed modes that involve CC stretching, CH3 bending, and CO stretching. This work conclusively proves the existence of stable acetone enolate species on a metal single-crystal surface and provides its first detailed characterization.