Organoscandium chemistry
Organoscandium chemistry is an area with organometallic compounds focused on compounds with at least one carbon to scandium chemical bond. The interest in organoscandium compounds is mostly academic but motivated by potential practical applications in catalysis, especially in polymerization. A common precursor is scandium chloride, especially its THF complex.
As with the other elements in group 3 – e.g. yttrium, forming organoyttrium compounds – and the lanthanides, the dominant oxidation state for scandium in organometallic compounds is +3. The members of this group also have large ionic radii with vacant s,p and d orbitals and as a result they behave as hard Lewis acids and tend to have high coordination numbers of 9 to 12. The metal to ligand chemical bond is largely ionic.
Illustrative complexes
Sc(III) derivatives
Many organoscandium compounds have at least one cyclopentadienyl-type ligand. The reaction of scandium trichloride with two equivalents of sodium cyclopentadienide produces the chloride-bridged dimer:Cp3Sc is a polymer wherein one third of the Cp ligands serving as bridging ligands.
Bulkier cyclopentadienide ligands give monoscandium derivatives, e.g. 2ScCl. The corresponding alkyls polymerize alkenes.
The synthesis of a trisscandium complex is analogous to the above methods, involving the reaction of ScCl3 with allyl potassium in THF solution, The product is Sc32 wherein two allyl ligands are η3 coordinated and one allyl ligand is η1.