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

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