Synthesis and ligand exchange reactions of (pentamethylcyclopentadienyl)lanthanum aryloxides

Cp*La(OAr)2 (Cp* = η5-C5Me5) is easily accessible by the reaction of La(OAr)3 with Cp*Li. Addition of THF yields the adduct Cp*La(OAr)2(THF)2. Both compounds disproportionate in solution with formation of equilibrium mixtures with comparable amounts of Cp*La(OAr)2, La(OAr)3 and Cp*2LaOAr. The equilibria were studied at various temperatures and thermodynamic parameters were determined from the temperature dependence of the equilibrium constants.