Complex hydrogen bonded cations. The imdazole/imidazolium complex cation

Abstract

. Can. J. Chem. 54, 2458 (1976). The salts (ImH+)X-, Im = imidazole, X-= PFs-, BF4-, or Cl0,-have been prepared in solution, and the perchlorate salt has been crystallised. The molecularity implied by the formula is confirmed in solution by Job's method, and for the crystals gravimetrically. In MeCN the association constant is -8 M-!. Infrared spectra of solution and crystals are similar, independent of counter ion, and indicate an asymmetric single minimum proton potential. The pronounced doublet in the NH stretching band of the H bridged complex, and replaced by a single band in the D bridged analogue, is not indicative of proton tunnelling. The X-ray structure is compatible with this interpretation of the spectra. On a prepare, en solution, les sels (ImH+)X-, Im = imidazole, X-= PFsM, BF4-ou C104-et le sel perchlorate a Ct C cristallisk. La molCcularit6 impliquk par la formule est confirm& en solution par la mCthode de Job et pour les cristaux d'une f a~o n gravimitrique. Dans le MeCN, la constante d'association est approximativement -8 M-1. Les spectres infrarouges en solution et sous forme de cristaux sont similaires, indkpendants de l'anion et indiquent la presence pour le proton d'un potentiel asymktrique comportant un seul minimum. Le doublet t r b prononcC dans la bande NH d'klongation du complexe pontC avec l'hydrogkne qui est remplacC par une bande unique dans l'analogue pontC avec du deuterium, n'indique pas la prCsence d'un effet de tunnel du proton. La structure dCtermin& par rayons-X est compatible avec cette interprktation du spectre.[Traduit par le journal]

Proton conducting plastic crystal electrolytes based on pivalic acid

“…This has given rise to a eutectec in the imidazole-rich domain at 293 K and another in the pivalic aciddomain at 308 K. This behaviour is typical of imidazole-acid mixtures and similar phase diagrams were reported for imidazole with H 2 SO 4 [2], or HTFSI [24] or HBF 4 [25] systems.…”

“…Although imidazole is less basic than triethylamine (pK b 11), it is basic enough to open the dimeric cycle. Mixtures of imidazole and strong acids like bis(triflouromethanesulfonyl)imide (CF 3 SO 2 ) 2 NH amide [24], HBF 4 (HPF 6 , HClO 4 ) [25] or H 2 SO 4 [2] were reported previously. The phase diagram of the imide mixture revealed the formation of a eutectic between the equimolar salt and either imidazole or the acid.…”

Formation of acid–water hydrogen bonds with large proton polarizability and molecular processes with dissociation of acids in the pKa range 0–4

“…With long N+H...N N-.-H+N bonds, band splitting and band-like structures of the continua were explained by various authors (28,(32)(33)(34)(35) as being caused by Fermi resonance of the fundamental transitions of the hydrogen bonds with combinational vibrations. Finally, Wolff and co-workers (36, 37) explained the fine structure of bands observed with carboxylic acids on the same basis.…”

Structurally symmetrical, easily polarizable hydrogen bonds between side chains in proteins and proton‐conducting mechanisms. III

“…The doublet bandlike structure of the continuum is caused by Fermi resonance of the proton fundamental transitions with combinational vibrations. [15][16][17][18] The fact that these N+H-N * N--H+N bonds are relatively long is confirmed by crystallographic data obtained with semiprotonated pyrazine and triethylenediamine complexes. In these cases, the hydrogen bond length obtained was 2.85 or 2.84 A, r e s p e c t i~e l y .~~~~~ A comparison of the results obtained here with earlier results with (LHis), shows a characteristic difference.…”