Diminished cage effect in solid p-H2: Infrared spectra of ClSCS, ClCS, and ClSC in an irradiated p-H2 matrix containing Cl2 and CS2

Irradiation of a p-H(2) matrix containing Cl(2) and CS(2) at 3.3 K with laser emission at 340 nm followed by annealing of the matrix produced main features at 1479.5 and 1480.8 cm(-1). These lines are attributed to nu(1) (SCS antisymmetric stretching) mode of ClSCS. Irradiation of the matrix at 355 nm decomposes ClSCS. Products CS (1272.2 and 1271.1 cm(-1)), ClCS (1193.9/1191.9 and 637.5 cm(-1)), and ClSC (1137.0 cm(-1)) were observed upon annealing. The assignments were based on comparison of observed vibrational wavenumbers and (13)C- and (34)S-isotopic ratios with those predicted with density-functional theories (B3LYP and BPW91/aug-cc-pVTZ). These results demonstrate that the cage effect of solid p-H(2) is diminished so that isolated Cl was produced via photodissociation of Cl(2) in situ and subsequently reacted with CS(2) to form ClSCS, but not ClC(=S)SCl, upon annealing; typically ClC(=S)SCl was produced as the major product on irradiation of noble-gas matrices containing Cl(2) and CS(2). Observation of ClSCS but not ClCS(2) is consistent with the theoretical prediction that only formation of the former proceeds via a barrierless path. Similarly, upon irradiation of ClSCS at 355 nm, Cl, CS, and CS(2) were produced; subsequent annealing of the irradiated matrix produced ClSC and ClCS via barrierless paths.