Imidazolium-based ionic liquids with large weakly coordinating anions. (24th January 2017)

• Record Type: Journal Article
• Authors: Levason, William; Pugh, David; Reid, Gillian
• Is Part Of: New journal of chemistry. Volume 41:Number 4(2017)
• Page Start: 1677
• Page End: 1686
• Publication Date: 2017-01-24
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c6nj03674k
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : An investigation into the intramolecular interactions in a series of imidazolium salts with weakly coordinating anions reveals that it is possible to control the strength and location of hydrogen bonding by varying the substituents on the imidazolium cation. Abstract : Eight imidazolium-based salts with the weakly-coordinating anions [BAr F ] − and [Al(O t C4 F9 )4 ] − ([BAr F ] − = tetrakis{3, 5-bis(trifluoromethyl)phenyl}borate) have been synthesized. Characterization by 1 H NMR spectroscopy shows that the salts are fully dissociated in solution. Six examples have been further characterized by X-ray crystallography, revealing that weak hydrogen bonds do occur in the solid phase between the imidazolium cations and weakly coordinating anions. Comparison with the bulky [IDiPPH] imidazolium cation (IDiPPH = 1, 3-bis{2, 6-bis(diisopropyl)phenyl}imidazolium) shows that large steric bulk close to the imidazolium protons can preclude hydrogen bonds from forming. Differential scanning calorimetry of the salts reveal that all are thermally stable up to 200 °C which renders them as potentially suitable background electrolytes for electrochemical processes which take place at elevated temperatures.