LiSc(BH₄)₄: A Novel Salt of Li⁺ and Discrete Sc(BH₄)₄⁻ Complex Anions

LiSc(BH4)4 has been prepared by ball milling of LiBH4 and ScCl3. Vibrational spectroscopy indicates the presence of discrete Sc(BH4)4− ions. DFT calculations of this isolated complex ion confirm that it is a stable complex, and the calculated vibrational spectra agree well with the experimental ones. The four BH4− groups are oriented with a tilted plane of three hydrogen atoms directed to the central Sc ion, resulting in a global 8 + 4 coordination. The crystal structure obtained by high-resolution synchrotron powder diffraction reveals a tetragonal unit cell with a = 6.076 Å and c = 12.034 Å (space group P-42c). The local structure of the Sc(BH4)4− complex is refined as a distorted form of the theoretical structure. The Li ions are found to be disordered along the z axis.