Scandium chloride

Chemical and physical properties

ScCl₃ crystallises in the layered BiI₃ motif, which features octahedral scandium centres. Monomeric ScCl₃ is the predominant species in the vapour phase at 900 K, the dimer Sc₂Cl₆ accounts for approximately 8%. The electron diffraction spectrum indicates that the monomer is planar and the dimer has two bridging Cl atoms each Sc being 4 coordinate.

Reactions

ScCl₃ dissolves in water to give [Sc(H₂O)₆]³⁺ ions. In fact, samples of ScCl₃ converts to this hexahydrate upon exposure to air. The structure of the hexahydrate is trans-[ScCl₂(H₂O)₄]Cl·2H₂O. With the less basic ligand tetrahydrofuran, ScCl₃ yields the adduct ScCl₃(THF)₃ as white crystals. This THF-soluble complex is used in the synthesis of organoscandium compounds. ScCl₃ has been converted to its dodecyl sulfate salt, which has been investigated as a "Lewis acid-surfactant combined catalyst" (LASC) in aldol-like reactions.

Reduction

Scandium(III) chloride was used by Fischer et al. who first prepared metallic scandium by electrolysis of a eutectic melt of scandium(III) chloride and other salts at 700-800 °C.

ScCl₃ reacts with scandium metal to give a number of chlorides where scandium has an oxidation state <+3, ScCl, Sc₇Cl₁₀, Sc₂Cl₃, Sc₅Cl₈ and Sc₇Cl₁₂. For example, reduction of ScCl₃ with scandium metal in the presence of caesium chloride gives the compound CsScCl₃ which contain linear chains of composition Sc^IICl₃⁻, containing Sc^IICl₆ octahedra sharing faces.

Uses

Scandium(III) chloride is found in some halide lamps, optical fibers, electronic ceramics, and lasers.