Synthesis and characterization of a series of mixed-cation borohydrides of scandium: [Cat][Sc(BH4)4], [Cat] = [Me4N], [n-Bu4N], and [Ph4P]

•[Cat][Sc(BH4)4], [Cat] = [Me4N], [n-Bu4N] and [Ph4P] were prepared and purified.•The crystal structures of above compounds were solved and refined from powder data.•These compounds decompose thermally above 175 °C with emission of organic products.•[n-Bu4N][Sc(BH4)4] melts at 88 °C which renders it a rare scandium-based ionic liquid.

Three organic mixed-cation borohydrides of scandium: [Cat][Sc(BH4)4], [Cat] = [Me4N], [n-Bu4N], and [Ph4P], denoted 1, 2 and 3, respectively, have been prepared and characterized. Compounds 1 and 3 are isostructural to the analogous rare earth borohydrides crystallizing in Pnma and I41/a space group, respectively. Compound 2 crystallizes in Pnna space group adopting structure of [Bu4N][FeCl4], which is different from that of its yttrium analogue (P21/c). The thermal decomposition of these substances starts above ca. 175 (compound 2), 195 (3), and 215 °C (1), and proceeds with evolution of volatile organic products. The thermal decomposition of 2 and 3 is preceded by melting at ca. 88 and 153 °C, respectively, which renders the compound 2 an ionic liquid. The compounds 2 and 3 are well soluble in various organic solvents and can be easily purified via dichloromethane extraction.

Graphical abstractThe crystal structures of [Cat][Sc(BH4)4], [Cat] = [Me4N], [n-Bu4N] and [Ph4P] which were prepared mechanochemically, purified and characterized.Figure optionsDownload full-size imageDownload as PowerPoint slide