On the synthesis of monopentamethylcyclopentadienyl derivatives of yttrium, lanthanum, and cerium

Two routes leading to monopentamethylcyclopentadienyl-yttrium, -lanthanum and -cerium complexes have been explored. Transmetallation of LnCl3(THF)x with Cp*Li (Cp* = C5Me5) proved useful only in some particular cases. Acid-base reactions of homoleptic complexes LnR3 with Cp*H generally gave Cp*2LnR compounds, although Cp*LnR2 complexes were observed as intermediates. The mono-Cp* complex Cp*Y(o-C6H4CH2NMe2)2 was obtained from Y(o-C6H4CH2NMe2)3 and Cp*H, and is the first salt-free mono-Cp* yttrium complex with two carbyl ligands.