Photochemistry of XCH2CN (X = -Cl, -SH) in Argon Matrices.

We report infrared spectra and photochemical behavior of the potentially astrochemically significant species, mercaptoacetonitrile (HS-CH2C≡N) and, for comparison purposes, chloroacetonitrile (Cl-CH2C≡N), both suspended in an argon matrix at 6 K. Photolytic formation of the isocyano products HS-CH2-NC and Cl-CH2-NC were observed as well as CH3NSC and CH3SCN (in HS-CH2CN photolysis). While no dissociation products were observed for Cl-CH2-CN, photolysis of HS-CH2-CN produced compounds necessitating the loss of the CN group to form CH2═S, the SH group to form H2C-CN and HC-CN, or both CN and SH to form CH3 and CH4. Observation of emission spectra upon annealing indicates the presence of free sulfur atom in matrices of photolyzed HS-CH2-CN.