Chlorocyanoborates: Synthesis, Spectroscopic and Structural Characterization, and Properties of Ionic Liquids

A set of first mixed chlorocyanoborates was synthesized and fully characterized by elemental analysis, NMR and vibrational spectroscopy. Two different synthetic approaches were developed: Exchange of chlorine against CN in case of [BCl3(CN)](-) and reaction of [BHx(CN)(4-x)](-) with Cl-2 or tBuOCl for the generation of [BClx(CN)(4-x)](-) (x = 1, 2). The single-crystal structures of [Ph4P][BCl2(CN)(2)] and [Ph4P][BCl3(CN)] were derived from X-ray diffraction experiments. [EMIm][BClx(CN)(4-x)] (x = 1-3) and [BMPL][BClx(CN)(4-x)] (x = 1, 2) were found to be low-viscosity room temperature ionic liquids. [EMIm][BCl(CN)(3)] (18.6 mPa center dot s) and [EMIm][BCl2(CN)(2)] (19.6 mPa center dot s) are even less viscous than the well-known [EMIm][B(CN)(4)] (EMIm-TCB, 22.6 mPa center dot s). Mono- and dichlorocyanoborates were studied by CV and found to provide large electrochemical windows. Especially [EMIm][BCl(CN)(3)] reveals a high specific conductivity (14.1 mS cm(-1)).