Preparation and Structures of Some S-N and S-Se-N Heterocycles

Abstract

<p>The interest in the metal-like superconducting polymer poly(sulfur nitride) has inspired numerous studies of other sulfur-nitrogen compounds. This thesis deals with the preparation and structures of cyclic S-N cations and S-N heterocyles containing selenium.</p> <p>The reactions of S₄N₄ with Lewis acids AlCl₃ and HSO₃F have given two new S₄N₄²⁺ salts, (S₄N₄)(AlCl₄)₂ and (S₄N₄)(SO₃F)₂. A study of their X-ray structures as well as those of (S₄N₄)(Sb₃F₁₄)(SbF₆) and (S₄N₄)(SbCl₆)₂ have shown that the S₄N₄²⁺ cation has a planar form and a nonplanar form. A normal coordinate analysis has been carried out on the planar S₄N₄²⁺ ion based on the vibrational data obtained for (S₄¹⁵/¹⁴N₄)(AlCl₄)₂ and (S₄N₄)(SO₃F)₂. The reaction of S₄N₄ with H6O₃F also produced the (S₆N₄)(SO₃F)₂ and (S₆N₄)(S₂O₂F)₂ salts, whose crystal structures are reported. The last compound contains the previously unreported S₂O₂Fˉ anion.</p> <p>S₄N₄ has been shown to react with the homopolyatomic cations S₈²⁺, Te₆⁴⁺ and Se₈²⁺/Se₄²⁺ to give S₆N₄²⁺, S₃N₂⁺ and the previously unreported Se₄S₂N₄²⁺ cation, respectively. The crystal structures of (S₃N₂)(AsF₆), (S₆N₄)(AsF₆)₂, (Se₄S₂N₄)(AsF₆)₂ and (Se₄S₂N₄)(SbF₆)₂ are reported along with their infrared spectra. The S₆N₄²⁺ and Se₄S₂N₄²⁺ cations are dimeric in that they contain two five-membered S₃N₂⁺ or Se₂SN₂⁺ rings linked by "long" S--S or Se--Se bonds.</p> <p>Uv-visible absorption and ESR spectra obtained on all the AsF₆- salts suggested that the dimers dissociate to monomers in solution. Magnetic susceptibility data for (S₃N₂)(AsF₆) have confirmed that this salt contains a radical with one unpaired electron. The magnetic susceptibility and differential scanning calorimetric measurements obtained for (S₆N₄)(AsF₆)₂ and (Se₄S₂N₄)(AsF₆)₂ have shown that both compounds undergo a reversible first-order phase transition coincident with magnetic behaviour that is consistent with a dimer-monomer interconversion.</p> <p>A study of the reactions of S₄N₄ and S₃N₃Cl₃ with Se₂Cl₂ and SeCl₄ resulted in the preparation and the X-ray crystallographic study of the compounds (S₅N₅)(SeCl₅) and SeS₂N₂Cl₂. The (S₅N₅)(SeCl₅) salt is the first well-characterized example of a compound containing the pentachloroselenate (IV) anion. The compound SeS₂N₂Cl₂ contains neutral SeS₂N₂Cl₂ molecules as well as the ions SeS₂N₂Cl⁺ and Clˉ in the same crystal. The ⁷⁷Se- and ¹⁵N-NMR spectra of SeS₂¹⁵/¹⁴N₂Cl₂ in H₂SO₄ is reported and vibrational data obtained for SeS₂¹⁵/¹⁴N₂Cl₂ and S₃¹⁵/¹⁴N₂Cl₂ are discussed.</p>