title: Halogenated Carboxonium Salts: Preparation and Structural Analysis.
abstract: We have studied the preparation and isolation of the halogenated alkylidene oxonium salts CH(3)OCHX(+)MF(6)(-) (X = Cl, F; M = As, Sb). Addition of dichloromethylmethylether at -78 degrees C to the superacidic media HF/MF(5) resulted in the formation of the chlorine compounds CH(3)OCHCl(+)MF(6)(-), whereas at -65 degrees C the fluorinated salts CH(3)OCHF(+)MF(6)(-) are formed by a chlorine/fluorine exchange. The salts are characterized by their low-temperature IR and Raman spectra. Additionally, the crystal structures of the hexafluoroantimonates are presented. The structures of the cations turned out to be different in some points. The salt CH(3)OCHF(+)SbF(6)(-) crystallizes in the monoclinic space group P2(1)/c with 4 molecules in the unit cell and a = 9.942(2), b = 7.454(2), and c = 10.297(3) Å; beta = 111.27(2) degrees. The salt CH(3)OCHCl(+)SbF(6)(-) crystallizes in the monoclinic space group P2(1)/c with 4 formula in the unit cell and a = 5.970(3), b = 12.019(5), and c = 10.994(5) Å; beta = 92.59(3) degrees.
authors.affiliation: Anorganische Chemie, Fachbereich Chemie der Universität Dortmund, D-44221 Dortmund, Germany, and Institut für Anorganische und Analytische Chemie der Freien Universität Berlin, D-14195 Berlin, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Minkwitz
authors.forename: Stefan
authors.initials: S
authors.lastname: Reinemann
authors.forename: Oliver
authors.initials: O
authors.lastname: Blecher
authors.forename: Hans
authors.initials: H
authors.lastname: Hartl
authors.forename: Irene
authors.initials: I
authors.lastname: Brüdgam