Elemental Sulfur and Sulfur-Rich Compounds I

Abstract

The molecular composition as well as the physical properties (including spectra) of liquid sulfur Liquid Sulfur properties are reviewed starting with a historic Introduction to explain the terms π-sulfur π-Sulfur properties and μ-sulfur μ-sulfur properties . At all temperatures the melt contains homocyclic rings of between 6 and at least 35 atoms with S 8 as the majority species as well as polymeric sulfur polymeric sulfur (S ∞) which becomes a major component only above 170 °C. The polymer probably consists of very large rings large ring at temperatures below 157 °C but above this temperature very long diradicalic chains occur in addition. At temperatures above 300 °C highly colored small molecules like S 3 and, at even higher temperatures, S 4 can be detected spectroscopically. According to quantum-chemical calculations branched rings branched ring (clusters) will be minor components at temperatures near the boiling point only. The temperature dependence of the composition is explained and the various polymerization theories polymerization theorie for the transformation of S 8 into S ∞ as well as the molecular nature of the polymer are discussed. In addition, the various analytical techniques applied to solve the composition problem of liquid sulfur are described.