Low Melting Tetracyanidoborate Salts with Alkyl‐, Arylammonium, and Pyridinium Cations: Syntheses, Structures, Properties.

The syntheses and single crystal structures of five new tetracyanidoborate salts with N‐based cations are described. Three of these compounds contain cations with acidic H atoms. The H‐bond strength, expressed by D‐A distances is correlated with a shift of the CN stretching mode frequency in the IR spectra. Melting points are found between 59 °C and 214 °C, i. e. at the borderline between ionic liquids and molten salts. Isothermal annealing indicates slow decomposition. Solubility tests in polar solvents show a strong dependence on the cation.