Related Experiment Video
Updated: May 30, 2026
From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding
Published on: March 24, 2018
Na[B(hfip)4] (hfip = OC(H)(CF3)2): a weakly coordinating anion salt and its first application to prepare ionic
Safak Bulut1, Petra Klose, Ingo Krossing
1Albert-Ludwigs-Universität Freiburg, Institut für Anorganische und Allgemeine Chemie, Freiburg Institute of Advanced Studies (FRIAS), Albertstr., 21, D-79104, Freiburg, Germany.
Abstract:
The fast, high yield synthesis and full characterization of Na[B(hfip)(4)] (hfip: OC(H)(CF(3))(2)) from NaBH(4) and hexafluoroisopropanol (hfipH) is presented. By anion metathesis, five [B(hfip)(4)](-) salts with classical/functionalized ionic liquid (IL) cations with melting points between 0 ([C(6)MIM](+)[B(hfip)(4)](-)) and 113 °C ([C(4)MMorph](+)[B(hfip)(4)](-)) were prepared. Four of these qualify as ILs and one as room temperature IL (RTIL). The properties of the borate anion [B(hfip)(4)](-) and its aluminum analogue [Al(hfip)(4)](-) were compared based on the available structural information from XRD. Viscosities (10.3 (90 °C) to 855 (0 °C) mPa s(-1)) and conductivities (0.603 (30 °C) to 4.844 (90 °C) mS cm(-1)) were measured between 0 and 90 °C, and described by the Vogel-Fulcher-Tammann (VFT) equations. The properties of the [B(hfip)(4)](-) ILs were analyzed in the context of the anion-dependent molecular volume V(m)-viscosity-/conductivity-correlations, also in comparison to ILs with [BF(4)](-)/[PF(6)](-), [N(CN)(2)](-), [Tf(2)N](-) and [Al(hfip)(4)](-) counterions. The viscosities and conductivities of [B(hfip)(4)](-) ILs are slightly inferior to [Al(hfip)(4)](-) ILs, similar to/better than all other anions given above. According to the Walden plots, the ionicity of the [B(hfip)(4)](-) ILs may at least be classified as "good". By sharp contrast to the [Al(hfip)(4)](-) ILs, the [B(hfip)(4)](-) ILs have good stability against humidity/water. Thus, handling of [B(hfip)(4)](-) ILs in an open laboratory atmosphere over hours and days is allowed and further facilitates the use of this new IL class.
Related Concept Videos
02:54Ions as Acids and Bases
Salts are ionic compounds composed of cations and anions, either of which may be capable of undergoing an acid or base ionization reaction with water. Aqueous salt solutions, therefore, may be acidic, basic, or neutral, depending on the relative acid-base strengths of the salt’s constituent ions. For example, dissolving the ammonium chloride in water results in its dissociation, as described by the equation:
02:45Alkyl Halides
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
03:34Ionic Compounds: Formulas and Nomenclature
02:42Ionic Crystal Structures
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
02:48Ionic Bonding and Electron Transfer
03:13Intermolecular Forces