Shao Xin, Wu Zhuang, Wang Lina, Rauhut Guntram, Zeng Xiaoqing
Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai 200433, China.
Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
J Phys Chem Lett. 2023 Nov 23;14(46):10450-10456. doi: 10.1021/acs.jpclett.3c02526. Epub 2023 Nov 14.
The mercaptomethyl radical (·CHSH) is a higher-energy isomer of the methylthio radical (CHS·) that has been proposed as an important intermediate in atmospheric and interstellar sulfur chemistry. Herein, we report the spectroscopic identification of ·CHSH during the UV (365 nm) photolysis of CHS· in a solid Ar-matrix at 10 K. Upon subsequent irradiation at 266 nm, the dehydrogenation of ·CHSH to yield CS via the intermediacy of the elusive thioformyl radical (HCS·) has also been observed. The characterization of ·CHSH and HCS· with matrix-isolation IR and UV-vis spectroscopy is supported by C-isotope labeling and quantum chemical calculations at the CCSD(T)-F12a/cc-pVTZ-F12 level using configuration-selective vibrational configuration interaction theory (VCI). The disclosed photochemistry of ·CHSH provides new insight into understanding the chemical evolution of organosulfur molecules in the interstellar medium (ISM).
巯基甲基自由基（·CHSH）是甲硫基自由基（CHS·）的一种高能异构体，它被认为是大气和星际硫化学中的重要中间体。在此，我们报告了在10 K的固态氩基质中，CHS·在紫外光（365 nm）光解过程中·CHSH的光谱鉴定。在随后266 nm的照射下，还观察到·CHSH通过难以捉摸的硫甲酰基自由基（HCS·）中间体脱氢生成CS。使用构型选择性振动构型相互作用理论（VCI）在CCSD(T)-F12a/cc-pVTZ-F12水平上进行的碳同位素标记和量子化学计算，支持了用基质隔离红外光谱和紫外可见光谱对·CHSH和HCS·的表征。所揭示的·CHSH光化学为理解星际介质（ISM）中有机硫分子的化学演化提供了新的见解。
