THE HEXAFLUOROCHLORATE(V) ANION, CLF6-

The low-temperature reactions of either N(CH3)4F or CsF with ClF5 in CH3CN solutions produce white solids, which on the basis of material balances and low-temperature Raman spectra, contain the ClF6- anion. The similarity of the Raman spectrum of ClF6- to that of the octahedral BrF6- ion indicates that ClF6- is also octahedral and that the free valence electron pair on chlorine is sterically inactive. The existence of the ClF6- anion was further supported by an 18F exchange experiment between ClF5 and 18F-labeled FNO that showed complete randomization of the 18F isotope among the two molecules. A high-field 19F NMR study of neat ClF5 and ClF5 in anhydrous HF solution in the presence and absence of excess CsF has provided accurate measurements of the ClF5 NMR parameters including, for the first time, both 37/35Cl secondary isotopic 19F NMR shifts. Moreover, the NMR study also supports the existence of ClF6-, showing that ClF5 undergoes slow chemical exchange with excess CsF in anhydrous HF at room temperature. © 1990, American Chemical Society. All rights reserved.