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Oxyfluorides, oxyfluorosulphates and oxycations of the halogens and selenium

University of British Columbia

Alternate routes for the preparation of chloryl fluorosulphate, ClO₂SO₃F, have been found. Evidence for the existence of the chloronium cation, ClO₂⁺, as a red-coloured species in fluorosulphuric acid, HSO₃F, has been obtained from electrical conductivity measurements, employing ClO₂SO₃F and (ClO₂)₂S₃O₁₀, dichloryl trisulphate, as solutes. nuclear magnetic resonance and uv-visible spectroscopy were also used to study solutions of ClO₂SO₃F in HSO₃F, and are in agreement with the conductivity results. The infrared and Raman spectra of the white solids, chloryl hexafluoroarsenate, chloryl hexafluoroantimonate and dichloryl hexafluorostannate have been obtained. The observed vibrations have been interpreted in terms of ionic compounds where strong cation-anion interaction via fluorine bridging results in a symmetry lowering of the anion. The effect of this interaction is also seen in the Mossbauer spectrum of (ClO₂)₂SnF₆ where a non-zero quadrupole splitting is found. All compounds dissolve in HSO₃F to give red-coloured solutions as a result of the formation of ClO₂⁺ cations. Tn addition, conductivity measurements show chloryl fluoride, ClO₂F, to be completely'.dissociated in HSO^F and to form ClO₂⁺ cations and SO₃F⁻ anions. The vibrational spectra of ClF₂AsF₆, ClF₂SbF₆ and Br₂SbF₆ have been recorded. In all compounds, various degrees of anion-cation interaction are found, resulting in the lowering of the symmetry of the anion. In addition, strong coupling of the vibrational modes for Br₂SbF₆, are observed. An alternate route to the preparation of KBr(SO₃F)₃ was found. A Raman spectrum of this compound indicates a square planar configuration for the anion with polar bromine-oxygen bonds. The Raman spectra obtained for the tris-fluorosulphates I(SO₃F)₃ and Br(SO₃F)₃ indicates the presence of two types of fluorosulphates groups and polymeric structures for these compounds. The structure of iodyl fluorosulphate, IO₂SO₃F, has been examined by Raman spectroscopy and conductivity measurements in HSO₃F. Evidence is found for discrete IO₂ groups linked by covalent bidentate fluorosulphate groups. A Raman spectrum of iodyl fluoride showed it to be dissimilar to the chlorine analogue, CIO₂F, and possess a polymeric structure. No discrete IO₂ groups are found in IO₂AsF₆ on the basis of the infrared spectrum. The new compound selenium (IV) oxyfluorosulphate, SeO(SO₃F)₂, has been prepared by the reaction of S₂O₆F₂ SeOCl₂ or SeO. The structure of SeO(SO₃F)₂ has been investigated mainly by Raman spectroscopy and conductimetry in HSO₃F. A self-dissociation process of the type, SeO(SO₃F)₂ = SeO(SO₃F)⁺ + SO₃F⁻ is suggested for SeO(SO₃F)₂ to explain the results of the physical methods. Also, the addition of SeOCl₂ to SeO(SO₃F)₂ results in the formation of SeO(SO₃F)Cl. Both SeO(SO₃F)Cl and SeO(SO₃F)₂ show unusually high Se=O vibrational stretching frequencies indicating polar Se-OSO₂F bonds.

Text

2011-03-31

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http://hdl.handle.net/2429/33135

Chemistry

University of British Columbia

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