A VALENCE FORCE FIELD FOR ALIPHATIC SULFUR COMPOUNDS - DITHIAALKANES

To obtain reliable vibrational assignments for use in statistical thermodynamic calculations for dithiaalkanes, the valence force field reported earlier for alkanethiols and thiaalkanes was extended to include the dithiaalkanes. The six additional force constants involved in the potential function of the dithiaalkanes were evaluated from observed wavenumbers of the following four molecules: 2,3-dithiabutane, 2,3-dithiapentane, 3,4-dithiahexane, and 2,2,5,5-tetramethyl-3,4-dithiahexane. The mean deviation of the calculated wave-numbers from the observed ones is 12.3 cm-1 or 1.1%, only slightly larger than for the alkanethiols and thiaalkanes. Previous assignments for the four investigated molecules were critically examined in the course of the molecular vibrational analysis and revised as necessary, and the probable conformations in which they can exist are presented and discussed. © 1969.