Structure and photochemistry of nitrous acid-methanethiol complexes in solid argon

The products formed in the CH3SH/HONO/Ar matrices after their deposition and after irradiation with lambda > 345 nm have been studied by FTIR spectroscopy and DFT/B3LYP/aug-cc-pVTZ method. The spectra recorded directly after matrix deposition indicated formation of the CH3SH center dot center dot center dot HONO complexes stabilized by the O-H center dot center dot center dot S bond. The irradiation of the matrices produced CH3SNO center dot center dot center dot H2O complexes. In more concentrated matrices the CH3SSCH3, (NO)(2), and N2O photoproducts were also detected. The presence of both dopants: CH3SH and HONO was essential in the formation of (NO)(2) and N2O in the studied systems. The reactions leading to photoproducts are proposed. The structures of the complexes present in the studied matrices, CH3SH center dot center dot center dot HONO and CH3SNO center dot center dot center dot H2O, are discussed on the basis of comparison of their theoretical spectra with the experimental ones. (C) 2012 Elsevier B.V. All rights reserved.