Unraveling sulfur chemistry in interstellar carbon oxide ices

Formyl radical (HCO center dot) and hydroxycarbonyl radical (HOCO center dot) are versatile building blocks in the formation of biorelevant complex organic molecules (COMs) in interstellar medium. Understanding the chemical pathways for the formation of HCO center dot and HOCO center dot starting with primordial substances (e.g., CO and CO2) is of vital importance in building the complex network of prebiotic chemistry. Here, we report the efficient formation of HCO center dot and HOCO center dot in the photochemistry of hydroxidooxidosulfur radical (HOSO center dot)-a key intermediate in SO2 photochemistry-in interstellar analogous ices of CO and CO2 at 16 K through hydrogen atom transfer (HAT) reactions. Specifically, 266 nm laser photolysis of HOSO center dot embedded in solid CO ice yields the elusive hydrogen-bonded complexes HCO center dot Greek ano teleiaGreek ano teleiaGreek ano teleiaSO(2) and HOCO center dot Greek ano teleiaGreek ano teleiaGreek ano teleiaSO, and the latter undergoes subsequent HAT to furnish CO(2)Greek ano teleiaGreek ano teleiaGreek ano teleiaHOS center dot under the irradiation conditions. Similar photo-induced HAT of HOSO center dot in solid CO2 ice leads to the formation of HOCO center dot Greek ano teleiaGreek ano teleiaGreek ano teleiaSO(2). The HAT reactions of HOSO center dot in astronomical CO and CO2 ices by forming reactive acyl radicals may contribute to understanding the interplay between the sulfur and carbon ice-grain chemistry in cold molecular clouds and also in the planetary atmospheric chemistry. The authors report photolytic H atom transfer reactions of HOSO center dot in astronomical CO & CO2 ices, forming reactive acyl radicals & molecular complexes with SO & SO2. Connecting the photochemistry of S oxides & C oxides in cold molecular clouds in the interstellar medium.