SS bonds are extraordinarily flexible and have properties that are observed only on isolated occasions for other homonuclear bonds: the bond lengths very between 1.8 and 3.0A, the bond angles between 90 and 180° and the dihedral angles between 0 and 180°; the bond energies amount to up to 430 kJ/mol. The SS stretching frequencies can appear over the range 177–820 cm−1 and force constants of 1.4 to 6.3 mdyne/A have been calculated. This variability is illustrated with examples containing isolated and cumulated SS bonds.

Properties of Sulfur‐Sulfur Bonds

Homocyclic sulfur molecules

SS-Bindungen sind aufiergewohnlich flexibel und haben Eigenschaften, die bei anderen homonuclearen Bindungen bisher nur vereinzelt beobachtet wurden : die Kernabstande variieren zwischen 1.8 und 3.0 A, die Valenzwinkel zwischen 90 und 180", die Diederwinkel zwischen 0 und 180", und die Bindungsenergien reichen bis 430 kJ/mol. SS-Valenzschwingungen konnen im Bereich 177-820 cm-' auftreten, und Kraftkonstanten von 1.4 bis 6.3 mdyn/A wurden berechnet. Diese Vielfalt wird an Beispielen mit isolierten und kumulierten SS-Bindungen erlautert.

Eigenschaften von Schwefel‐Schwefel‐Bindungen

We show that the density anomaly in sulfur near the polymerization transition observed by Borst and co‐workers can be explained, at least in part, as a manifestation of nonclassical critical behavior. We combine the lattice solution model recently proposed to study equilibrium polymerization in sulfur with a phenomenological assumption to produce a dramatic improvement over earlier theories. Some discrepancies between the theory and experiment remain.

On the density anomaly in sulfur at the polymerization transition

The reactions of sodium sulfide or disulfide with sulfur, when heated, are examined through Raman spectroscopy. It is shown that whatever the composition of the mixtures, the solid sodium sulfide or disulfide transforms into the crystalline α-Na2S4 phase in a first step, with α- or β-Na2S2 as an intermediate. The reaction, which proceeds when the sulfur melts, is assumed to be related to the polymerization−depolymerization mechanism responsible for the formation of smaller rings and sulfur chains in molten S8. This confirms the strong reactivity of the radical sulfur chain molecules. This solid α-Na2S4 formed may further react around 200 °C with Na2S in excess. This solid-state reaction leads to the formation of β-Na2S2. It is shown that, after the liquid of composition Na2S4 is heated above 400 °C, a glass is formed upon cooling. Annealing this glass around 124 °C yields a new γ-Na2S4 crystalline phase where the S42- anions have a smaller torsion angle. This new phase is metastable and transforms into th...

Raman Spectroscopy Study of the Reaction between Sodium Sulfide or Disulfide and Sulfur: Identity of the Species Formed in Solid and Liquid Phases.

ESR investigations on liquid sulphur and selenium

New method in calculating the polymerization parameters of liquid sulphur and selenium

A line shape matching procedure, programmed for a digital computer, is described. Based upon a least squares analysis the procedure enables one to select a line shape of a suitable analytical form and determine its parameters for the representation of an experimental single line absorption spectrum. The limits of reliability of the parameters found in this way are also calculated.

D.C. Koningsberger

Papers

ESR investigations on liquid sulphur and selenium

New method in calculating the polymerization parameters of liquid sulphur and selenium

Choice of line shape representation and reliability of line parameters for single line esr spectra