Editing Scandium (section)

===Halides and pseudohalides===
The [[halide]]s {{chem2|ScX3}}, where X= [[scandium chloride|Cl]], [[scandium bromide|Br]], or [[scandium triiodide|I]], are very soluble in water, but [[scandium fluoride|{{chem2|ScF3}}]] is insoluble. In all four halides, the scandium is 6-coordinated. The halides are [[Lewis acids]]; for example, [[scandium fluoride|{{chem2|ScF3}}]] dissolves in a solution containing excess fluoride ion to form {{chem2|[ScF6](3−)}}. The coordination number 6 is typical for Sc(III). In the larger Y<sup>3+</sup> and La<sup>3+</sup> ions, [[coordination number]]s of 8 and 9 are common. [[Scandium triflate]] is sometimes used as a [[Lewis acid]] catalyst in [[organic chemistry]].<ref>{{cite journal |doi =10.1055/s-1999-5997 |title= SYNLETT Spotlight 12: Scandium Triflate |author= Deborah Longbottom |journal= [[Synlett]] |year= 1999 |issue= 12 |pages= 2023 |volume =1999|doi-access= free }}</ref>