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Title: | Recent Synthetic and Structural Developments in Noble-Gas, Chlorine, Bromine, Iridium, and Group 6 Fluorine Chemistry |
Authors: | Bortolus, Mark R. |
Advisor: | Schrobilgen, Gary J. |
Department: | Chemistry and Chemical Biology |
Publication Date: | 2022 |
Abstract: | The candidate’s Ph.D. Thesis research exploits the fluorides of the noble-gases, chlorine, iridium, and the Group 6 oxide tetrafluorides to address specific knowledge gaps in fundamental inorganic fluorine chemistry. The compounds dealt with in these studies are potent oxidants that are extremely air-sensitive. Structural characterization methods included low-temperature (LT) Raman spectroscopy and LT single-crystal X-ray diffraction (SCXRD). Quantum-chemical calculations were used to aid vibrational mode assignments and to assess bonding. A goal of this research was to address the absence of mixed Xe(II)/Kr(II) and Xe(IV)/Kr(II) noble-gas compounds. This led to a synthetic, structural, and computational study of the first mixed Kr(II)/Xe(II) species, the [FKrFXeF]+ cation (as the [AsF6]– salt), and the first mixed Kr(II)/Xe(IV) compounds, obtained as the cocrystals ([Kr2F3][AsF6])2∙XeF4 and XeF4∙KrF2 that were isolated at LT from anhydrous HF (aHF) solvent. Although the fluoride-ion donor chemistries of the neutral X(V) (X = Cl, Br) fluorides and oxide fluorides are developed, the coordination chemistries of the X(V) cations [XF4]+, [XOF2]+, and [XO2]+ were largely unknown. The synthesis and structural characterization of the first Cl(V) coordination complex of XeF2, [O2Cl(FXeF)2][AsF6], is described. The reaction of α-[ClO2][AsF6] with XeF2 at −78 °C in anhydrous HF (aHF) solvent yields [O2Cl(FXeF)2][AsF6], which constitutes a rare example of noble-gas difluoride coordination to a main-group Lewis acid center. In a related study, the reactions of [BrO2][PnF6] with XeF2 in aHF were shown to yield [O2Br(FXeF)n][AsF6] (n = 1, 2) and [O2Br(FXeF)2][SbF6]. The complexes were characterized by LT Raman spectroscopy and SCXRD and provided the first examples of coordination complexes between a noble-gas difluoride and [BrO2]+. Another goal was to synthesize and structurally characterize the first example of an iridium oxyfluoride. The study focused on the reaction of IrO2 with the oxidative fluorinaters, ClF5 and ClF3, which yielded the Ir(V) complex, F5Ir---OClF and the first iridium oxyfluoro-anion salt, [ClO2]2[cyclo-(µ-OIrF4)3], where the iridium atoms are in the +5 (x2) and +6 oxidation states. This study also provided the first crystallographic characterization of endothermic OClF. At the outset of this research NgF2 (Ng = Kr, Xe) were known to form complexes with the intermediate-strength fluoride-ion acceptors, MOF4 (M = Cr, Mo, W), having the formulae NgF2·nMOF4 (n = 1, 2). However, FKrFb---WOF4 and FKrFb---MOF3Fbʹ---MOF4ʹ (M = Mo, W) defied characterization by SCXRD because they rapidly underwent redox decomposition during attempts to grow crystals. The syntheses and structural characterizations of FKrFb---WOF4 and the HF solvate, [--(F4OMo)(µ3-F)H---(µ-F)H--]∞, are described. The only TM complex of XeF4, F3XeFb---WOF4, was also synthesized and structurally characterized. Prior to this work, XeF4 coordination chemistry was limited to [Mg(XeF2)(XeF4)][AsF6]2, where XeF4 is F-coordinated to Mg2+. The reactions of MOF4 (M = Cr, Mo, W) with XeF6 were also studied with the aim to synthesize high-oxidation-state Group 6 oxyfluoro-anion salts of [XeF5]+ and [Xe2F11]+. Room-temperature reactions of XeF6 and CrOF4 in aHF and CFCl3 led to reductive elimination of F2 and the novel Cr(V) oxyfluoro-anion salts, [XeF5]2[Cr2O2F8]·2XeOF4 and [XeF5]2[Cr2O2F8]·2HF. The reaction of CrO2F2 and XeF6 gave [XeF5][Cr2O4F6], [XeF5][Cr2O4F6]·4HF, [XeF5][Cr2O4F6]·2XeOF4, and [XeF5][Xe2F11][CrO2F4], which provide the first crystallographically characterized Cr(VI) oxyfluoro-anions derived from CrO2F2. Reactions of MOF4 (M = Mo, W) with XeF6 in aHF solvent yielded [XeF5][M2O2F9] and [Xe2F11][MOF5], whereas the LT reaction of XeF6 and CrOF4 in aHF yielded [XeF5][HF2]·CrOF4. To circumvent [HF2]− formation, [Xe2F11][CrOF5] was synthesized in ClF2CCF2Cl (Freon-114), which provided the first SCXRD characterization of a [CrOF5]− salt. |
URI: | http://hdl.handle.net/11375/28194 |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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Bortolus_Mark_R_202212_PhD.pdf | 56.66 MB | Adobe PDF | View/Open |
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