Structure of nitrile-functionalized alkyltrifluoroborate salts

Two nitrile-functionalized alkyltriflouroborate anion based complexes [(Ph3P)(2)N][CH3CH(BF3)CH2CN] and [K(18-crown-6)][CH3CH(BF3)CH2CN] were synthesized and characterized by spectroscopic methods and single X-ray diffraction analysis. In the former complex no direct cation-anion (F -> N or F -> P) interactions are observed although F center dot center dot center dot H-C hydrogen bonds are present. In the later complex all three fluorine atoms interact with the potassium cation and C-H... F hydrogen bonds are also present. The EST-MS spectra in methanol solution of the potassium complex show similar anion-cation aggregation to that observed for ionic liquids, and comparisons between the two complexes and ionic liquid systems are made. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).