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

We report infrared spectra and photochemical behavior of the potentially astrochemically significant species, mercaptoacetonitrile (HS-CH 2 C≡N) and, for comparison purposes, chloroacetonitrile (Cl-CH 2 C≡N), both suspended in an argon matrix at 6 K. Photolytic formation of the isocyano products HS-CH 2 -NC and Cl-CH 2 -NC were observed as well as CH 3 NSC and CH 3 SCN (in HS-CH 2 CN photolysis). While no dissociation products were observed for Cl-CH 2 -CN, photolysis of HS-CH 2 -CN produced compounds necessitating the loss of the CN group to form CH 2 ═S, the SH group to form H 2 C-CN and HC-CN, or both CN and SH to form CH 3 and CH 4 . Observation of emission spectra upon annealing indicates the presence of free sulfur atom in matrices of photolyzed HS-CH 2 -CN.