Oxidative fluorination of diary1 diselenides, (RSe)2, with silver difluoride generates the corresponding arylselenium trifluorides, RSeF,, where R = C6H5, P-CH&H4, p-FC6H4, o-C2H5C6H4, and o-NO2C6H4. These compounds are moisture-sensitive crystalline solids. Molecular weight, infrared, and I9F NMR data are presented and discussed with regard to RSeF:, structures in solution and the solid state. A pseudo-trigonal-bipyramidal structure is proposed for the above compounds, except for o-NO2C6H4SeF3 for which a pseudo-octahedral structure is proposed. I9F NMR data show that rapid fluorine exchange occurs for the arylselenium trifluorides when R = C6H5, p-CH3C6H4, and p-FC6H4. Sterically restricted F exchange is observed for R = o-C2H5C6H4, while coordinatively restricted exchange is found for R = o-NO2C6H4. Assignments of the Se-F vibrational modes are given assuming local C, symmetry around Se. Infrared studies suggest only a limited tendency for RSeF, molecules to achieve maximum coordination in the solid state via intermolecular fluorine bridge bonding. Phenylseleninyl fluoride, C&%OF, is found to be a product of the reaction of C&,SeF, with water vapor or phenylseleninic acid. By potentiometric measurements with chlorine/chloride electrodes the mole fraction of NaCl in a NaC1-AlC1, melt saturated with NaCl at 175 OC was found to be 0.50209 (5). Furthermore, in the pC1 range of 3.885-5.034, the measured potential of the chlorine/chloride electrode at 175 OC could be rationalized by a combination of three reactions: (i) 2AlC1, a A12C17-The pK values (based on the molar units) of these reactions were found to be 7.052 (7), 6.9, and 14, respectively. By potentiometric measurements combined with Raman spectroscopy it was shown that the only complex of Se(1V) formed in the NaCl-AlCI,-SeCl, system at 175 OC in the pC1 range 1.183-4.662 was SeC13+. In the NaC1-A1C13-SeC14-Na20 system it was found that in the basic part of the system (i.e., pC1 <2.58) SeC13+ reacted with the oxide ions forming an oxochloro compound, whereas in the acidic part (Le., $1 >2.58) the oxide ions reacted with the chloroaluminate ions (instead of the SeC13+ ions) forming oxochloroaluminum compounds.
