Diminished cage effect in solid p-H-2: Infrared spectra of CISCS, CICS, and CISC in an irradiated p-H-2 matrix containing Cl-2 and CS2

Abstract

Irradiation of a p-H-2 matrix containing Cl-2 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 v(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 C-13- and S-34-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 CS2 to form ClSCS, but not ClC(=vS)SCl, upon annealing; typically ClC(vS)SCl was produced as the major product on irradiation of noble-gas matrices containing Cl-2 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. c 2010 American Institute of Physics. [doi: 10.1063/1.3386578]