Diminished cage effect in solid p-H₂: Infrared spectra of ClSCS, ClCS, and ClSC in an irradiated p-H₂ matrix containing Cl ₂ and CS₂

Irradiation of a p H₂ matrix containing Cl₂ and CS₂ 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 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 ¹³C - and ³⁴S -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 H₂ is diminished so that isolated Cl was produced via photodissociation of Cl₂ in situ and subsequently reacted with CS₂ 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 Cl₂ and CS₂. Observation of ClSCS but not ClCS₂ 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 CS₂ were produced; subsequent annealing of the irradiated matrix produced ClSC and ClCS via barrierless paths.