Ionic liquids containing the triply negatively charged tricyanomelaminate anion and a B(C₆F₅)₃ adduct anion
Publication date
2011-11-25
Document type
Research article
Author
Voss, Karsten
Becker, Martin
Villinger, Alexander
Emel'yanenko, Vladimir N
Kirchner, Barbara
Uhlig, Frank
Verevkin, Sergey P
Schulz, Axel
Organisational unit
Universität Rostock
Scopus ID
Pubmed ID
Series or journal
Chemistry - a European journal
Periodical volume
17
Periodical issue
48
First page
13526
Last page
13537
Peer-reviewed
✅
Part of the university bibliography
Nein
Keyword
Density functional calculations
Ionic liquids
Melaminates
Nitrogen heterocycles
Thermochemistry
Abstract
Room-temperature ionic liquids containing the triply charged tricyanomelaminate (tcmel) ion [C(3)N(6)(CN)(3)](3-) were synthesized. The 1-methyl-3-methylimidazolium (MMIm), 1-ethyl-3-methylimidazolium (EMIm), and 1-butyl-3-methylimidazolium (BMIm) salts of the tricyanomelaminate ion have glass transition temperatures (-6, -20, and -30 °C) similar to those found for the analogous monomeric dicyanoamide salts. They are thermally stable up to over 200 °C and dissolve in polar organic solvents. Addition of B(C(6)F(5))(3) to M(3) [tcmel] (M=Na, MMIm, EMIm, BMIm) yields salts containing the very voluminous adduct ion [C(3)N(6) {CN·B(C(6)F(5))(3)}(3)](3-) (tcmel_3B). The solid-state structure of [MMIm](3-) [tcmel] shows only long cation···anion contacts but in large number, while the solid-state structure of [Na(THF)(3)](3-) [tcmel_3B]·1.76 THF displays strong interactions of the sodium cation with the amido nitrogen atoms of the anion. Hence this adduct anion cannot be regarded as a weakly coordinating anion. A similar situation is found for the MMIm salt, [MMIm](3) [tcmel_3B]·2.66 CH(2)Cl(2), in which weak hydrogen bonds with the acidic proton of the MMIm ion are observed. On the basis of computations the energetics, structural trends, and charge transfer of adduct anion formation were studied.
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