MOLECULAR-STRUCTURE OF CIS-H2S3 AND TRANS-H2S3

The rotational spectra of cis-and trans-HSSSH have been complemented u p to 670 GHz ((r)Q(29) branch) and the spectra of several of its isoto pomers have been recorded between 70 and 300 GHz. The derived rotation al constants of HSSSH, (HSSSH)-S-34, (HSSSH)-S-34, HSSSD, and DSSSD pr ovide the experimental basis for for deriving a substitution structure (r(s)) for cis-HSSSH and and a r(epsilon I) structure for both specie s, i.e. cis-and trans-HSSSH. The r(epsilon I) bond distances and angle s are for the cis-conformer: R(SH)= 1.3435(14) Angstrom, R(SS) = 2.053 0(1) Angstrom, angle SSH = 97.37(15)degrees, angle SSS = 106.919(3)deg rees, angle SSS-SSH = 90.82(16)degrees, and for the trans-conformer: R (SH)= 1.3435(assumed) Angstrom, R(SS) = 2.0539(4) Angstrom, angle SSH = 97.2(7)degrees, angle SSS = 107.02(2)degrees, angle SSS-SSH = 87.7(4 )degrees. These experimental structural results are in good agreement with ab initio calculations. The spectra show no effect of internal ro tation, in agreement with a theoretical barrier estimate of similar to 2900 cm(-1). (C) 1997 Elsevier Science B.V.