Structural and spectroscopic studies of 2,5-dithiahex-3-yne

Abstract

The structure of 2,5-dithiahex-3-yne, CH₃SCCSCH₃, has been determined by electron diffraction in the gas phase to give (on the r_a-basis, and with e.s.d.)r(S—C_—) 1.671(2)Å, r(S—CH₃) 1.806(2)Å, ∠ CSC 102.7(2)° with the dihedral (torsion) angle ϕ(CSSC) 86 ± 5°. The gas photoelectron spectra (He I and He II) have been measured and interpreted with the aid of CNDO/2 molecular orbital calculations. The i.r., Raman, n.m.r. (¹H and ¹³C) and u.v./visible spectra have also been recorded. The results of these various measurements are used to show that there is no definite evidence of conjugation between the sulphur atoms and the acetylenic triple bond.