title: Alkoxy substituted halogenated closo-dodecaborates as anions for ionic liquids.
abstract: Halogenated and alkoxylated closo-dodecaborates [B12X11OR](2-) (X = Cl, Br; R = propyl, octyl, dodecyl) have been synthesized by halogenation of the known [B12H11OH](2-) anion followed by alkylation in the superbasic medium DMSO/KOH. The obtained sodium salts were transformed by simple metathesis reactions in aqueous solution to the tetrabutylammonium ([NBu4](+)) and 1-hexyl-3-methylimidazolium ([C6mim](+)) salts. All compounds were fully characterized by heteronuclear NMR, IR and Raman spectroscopy, ESI mass spectrometry, and thermal analytical measurements. Selected anions were also structurally characterized as their [Ph4P](+) salts by single crystal X-ray diffraction. The [C6mim](+) salts are thermally stable up to more than 300 °C and show clear melting points. Surprisingly, the compound [C6mim]2[B12Cl11O-propyl] having the short propyl group bound to the boron cluster shows the lowest melting point (96 °C) of all the investigated compounds. Thus this compound is a rare member of the class of ionic liquids consisting of dianions.
authors.affiliation: Fachbereich C - Anorganische Chemie, Bergische Universität Wuppertal, Gaußstr. 20, 42119 Wuppertal, Germany. carsten.jenne@uni-wuppertal.de.
authors.forename: Carsten
authors.initials: C
authors.lastname: Jenne
authors.forename: Christoph
authors.initials: C
authors.lastname: Kirsch