Synthesis, reactivity, structural, and computational studies of [C 6 F 5 Xe] + and [C 6 F 5 XeF 2] + salts
Duisburg (2005), XVI, 298 Bl. : Ill., graph. Darst.
Dissertation / Fach: Chemie
Fakultät für Chemie
Four new [C6F5Xe]+ salts, namely [C6F5Xe][B(CN)4], [C6F5Xe][B(CF3)4], [C6F5Xe][B(OTeF5)4], and [C6F5Xe][B(C6F5)4] were prepared by metathesis reactions of [C6F5Xe][BF4] and the corresponding salts, M[BY4] (Y = CN, CF3, OTeF5, and C6F5; M = K, Cs), in CH3CN at ambient temperature and isolated as pale yellow solids. Complete characterizations were accomplished in solution (NMR) and in the solid state (Raman and crystallography). The vibrational assignments for [C6F5Xe]+, [C6F5XeNCCH3]+, C6F5I, CH3CN were made with the assistance of quantum mechanical calculations carried out at the HF and DFT ((SDB-)cc-pVTZ) levels of theory. The thermal stability of all salts were examined in the solid state by Thermo-analytical DSC measurements and in CH3CN and, if possible, in CH2Cl2 solution by NMR spectroscopy. The parameters influencing the decomposition are shown and a mechanism is proposed. The ability of [C6F5Xe]+ salts to arylate aromatics was examined in detail on fluorobenzene. The parameters influencing the rate of reaction and the product distribution are shown and a mechanism is proposed. With access to CH2Cl2 soluble [C6F5Xe]+ salts, the rate of formation of C6F5XeF was fastened from 2 d to 1 h in comparable quality. The preparation of the unique organoxenon(IV) compound, [C6F5XeF2][BF4], was analyzed and the parameters influencing the synthesis were optimized. The salt was isolated as ochre yellow solid and fully characterized in solution and the solid state (NMR, Raman und X-Ray). The vibrational assignments for [C6F5XeF2]+, [C6F5XeF2∙NCCH3]+, [C6F5XeF2∙(NCCH3)2]+ and C6F5IF2 were made with the assistance of quantum mechanical calculations carried out at the HF and DFT ((SDB-)cc-pVTZ) levels of theory. It was able to prepare a second example of an organoxenon(IV) compound, [C6F5XeF2][B(CF3)4], whose instability in CH3CN solution prohibited it isolation as pure solid. The decomposition pathways of [C6F5XeF2]+ were analyzed and the factors that influenced the decomposition were studied. The evaluation of the oxidation strength of [C6F5XeF2]+ was investigated in systematic studies with Pn(C6F5)3 compounds (Pn = P, As, Bi) and C6F5Hal (Hal = Br, I) in CH3CN and aHF solution. The formation of (C6F5)3PnF2 (Pn = P, As und Bi) and C6F5IF2, respectively, was obtained.
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