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Anionic species formed in mixtures of 1-n-butyl-3-methylimidazolium chloride (BMICl) with different amounts of niobium pentachloride (NbCl 5 ) or zinc dichloride (ZnCl 2 ) were investigated by Raman spectroscopy. In the BMICl and NbCl 5 ionic mixtures the presence of the anion NbCl 6 − was detected for all compositions (molar fraction, X NbCl 5 ) and a mixture of this anion and the neutral Nb 2 Cl 10 in acid ones. Two different anions were observed for basic mixtures of BMICl and ZnCl 2 : ZnCl 4 2− .0 < X ZnCl 2 < 0.35/ and Zn 2 Cl 6 2− .X ZnCl 2 > 0.3/, whereas for acidic ones three species were detected: Zn 2 Cl 6 2− .X ZnCl 2 < 0.7/, Zn 3 Cl 8 2− .X ZnCl 2 > 0.7/ and Zn 4 Cl 10 2− .X ZnCl 2 > 0.7/. It has also been observed that in both cases, the formation of larger anions causes a shift of the C-H stretching modes to higher wavenumbers as the result of a decrease in the hydrogen bond between Cl and the hydrogens from the cation.

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A great variety of imines were efficiently isolated in high yields from the reaction of aldehydes and amines in ionic liquids. The ionic liquids could be recovered and reused for at least five cycles without loss in the yields being a useful alternative to dichloromethane or diethyl ether, which are the commonly used solvents for this reaction.