Syntheses and characterization of xenon oxide and oxide fluorides of xenon(VIII), osmium(VIII), iodine(VII), and xenon(II)

Abstract

<p>Xenon tetroxide was stabilized in SO2 ClF, BrF5 , and HF solvents rendering its 129 Xe and 17 O NMR spectroscopic characterization possible. The high symmetry about xenon in XeO4 allowed for the observation of the first 131 Xe resonance of chemically bonded xenon. Spin-lattice relaxation time measurements for 129 Xe and 131 Xe showed that the spin-rotation and the quadrupolar relaxation, respectively, are the predominent mechanisms of relaxation in XeO4 . The investigation of the 129 Xe NMR spectrum of [Na]4 [XeO6 ] in solution and solid state corrected the previously reported, erroneous value. Xenon tetroxide was shown to act as a Lewis acid towards CH3 CN solvent and fluoride ions yielding XeO4 (CH3 CN) and XeO4 F2 2- , respectively. The XeO4 (CH3 CN) adduct was characterized by 129 Xe NMR and Raman spectroscopy and contains the first example of a Xe(VIII)-N bond. The XeO4 F 22- anion was shown to exist as a mixture of its cis - and trans -isomers based on Raman spectroscopy. For the first time, XeO3 F2 was prepared in SO2 ClF, BrF5 , and HF solvents and characterized by 19 F and 129 Xe NMR spectroscopy. The novel XeO3 F 3- anion was prepared in low concentrations in SO2 ClF and BrF5 solvents and was identified by 19 F and 129 Xe NMR spectroscopy and shown to have a facial trioxo configuration. In the present work, the OsO4 F- anion was prepared and characterized by X-ray crystallography and vibrational spectroscopy as its N(CH3 )4+ salt. The OsO4 F 22- anion had been prepared in admixture with the OsO4 F- anion and was characterized by vibrational spectroscopy showing its cis -difluoro arrangement. The OsO 4 F- anion was shown to be identical to the anion that had been previously reported and charactized by vibrational and EXAFS spectroscopy and erroneously assigned as the cis -OsO 4 F22- anion. The Lewis acidbase reaction between OsO3 F2 and fluoride ions and CH3 CN yielded the OsO3 F3- anion and the OsO3 F2 (CH3 CN) adduct, respectively. The unambiguous identification of the OsO3 F3- anion as the exclusive, facial trioxo isomer was accomplished by determining the crystal structure of [N(CH3 )4 ][OsO3 F 3 ] and by vibrational spectroscopic characterization of the N(CH 3 )4+ and NO+ salts. The OsO 3 F2 (CH3 CN) adduct, however, exists as a mixture of its fac - and mer -isomers in solution and in the solid state based on 19 F and 15 N NMR and Raman spectroscopy. The Os(VIII) oxide fluoride, OsO3 F2 , acts as a Lewis base towards strong acids like AsF5 and SbF5 in HF solvent yielding [OsO3 F][AsF6 ], [OsO3 F][HF] 2 [AsF6 ], [Os2 O6 F3 ][AsF 6 ], [OsO3 F][HF][SbF6 ], and [OsO3 F][HF] 2 [SbF6 ], which were characterized by Raman spectroscopy. (Abstract shortened by UMI.)</p>