Ionic Liquids Containing the Triply Negatively Charged Tricyanomelaminate Anion and a B(C₆F₅)₃ Adduct Anion

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.

Redox Reactions Between Guanidine Electron Donors and Silver Dicyanamide: Synthesis of C,N Material Precursors and Coordination Polymers

“…Dicyanamide {[N(CN) 2 ] – , dca} salts are of considerable interest as precursors to C,N materials 5. Sodium dicyanamide was first reported in 1922 by Madelung and Kern,6 who also observed trimerization at high temperature (500 °C) to give sodium melaminate Na 3 [C 3 N 6 (CN) 3 ] 7,8. The thermal conversion of guanidinium dicyanamide, [C(NH 2 ) 3 ](dca),9 and guanylurea dicyanamide, [(H 2 N)C(O)NHC(NH 2 ) 2 ](dca),10 to give intermediates en route to C,N materials has been studied in detail (see Scheme ).…”

Tetracyanido(difluorido)phosphates M+[PF2(CN)4]−

“…[3] One major activity in designing new robust anions focusses on the synthesis of cyanide-based anions and their utilization in ILs. [4,[14][15][16][17][18][19][20][21][22][23][24][25][26] Salts bearing the tetracyanidoborate anion, [B(CN) 4 ] À ,w ere first obtained by Willner et al in the reaction of [Bu 4 N]X, BX 3 (X = Br, Cl) and KCN in toluene. [27] Am ore efficient synthesis for tetracyanidoborates on al arger scale starting from the readily available reagents K[BF 4 ], LiCl, and KCN was published by the same group in 2003 [23] along with studies of the thermal behavior of the mixed cyanidofluoridoborates, K[BF n (CN) 4Àn ]( n=1-3).…”

Pseudo Halide Chemistry in Ionic Liquids with Decomposable Anions

“…Syntheses of pseudohalide‐containing ionic liquids (IL) are usually carried out in biphasic systems, in which different solubilities of salts are utilized, or via salt metathesis reactions, in which a highly insoluble salt (often a silver halide) precipitates . Incomplete cation exchange and dissolved traces of metal halides in the ionic liquid are known problems for this synthetic route.…”