Acetylacetone in hydrogen solids: IR signatures of the enol and keto tautomers and UV induced tautomerization

► Mid-IR spectroscopy of enol and keto forms of acetylacetone in solid parahydrogen. ► Precise vibrational assignments based on anharmonic calculations. ► Higher keto/enol ratio in parahydrogen than in other matrices. ► UV induced tautomerization from enol to keto leading to samples containing only keto. ► Non-chelated enol forms are intermediates in the tautomerization process.