Normalschwingungen und Rotationsisomerie von Polysulfidionen S²⁻ n(n=4 - 8) / Fundamental Vibrations and Rotational Isomers of Polysulfide Anions, Sn ²⁻ (n = 4 - 8)

Raman spectra of (NH 4 ) 2 S 5 and S 4 Cl 2 (dichlorotetrasulfane) have been recorded, and force constants have been calculated for the pentasulfide ion using an extended Urey-Bradley force field with six independent force constants. K 2 S 5 like (NH 4 ) 2 S 5 is shown to contain helical S 5 2- (symmetry C 2 ) but Na 2 S 5 consists of cis-S 5 2- of symmetry C 5 . The force constants of S 4 2- and S 5 2- agree well with those of S 8 and have been used to calculate the fundamental vibrations of S 6 2- ) S 7 2- , and S 8 2- in different isomeric rotational conformations. The Raman spectrum of S 4 Cl 2 is compared with the vibrations calculated for isoelectronic S 6 2- .