Ct. Qian et al., SYNTHESIS AND CRYSTAL-STRUCTURES OF TRIS(2-METHOXYETHYLCYCLOPENTADIENYL)LANTHANIDE COMPLEXES, Journal of the Chemical Society. Dalton transactions, (6), 1996, pp. 955-960
The tris(2-methoxyethylcyclopentadienyl)lanthanide complexes [Ln(C(5)H
(4)CH(2)CH(2)OMe)(3)] (Ln = La, Pr, Nd, Gd or Y) were synthesized by t
he reaction of sodium 2-methoxyethylcyclopentadienide with the corresp
onding LnCl(3) and the products were characterized by elemental analys
es, mass, IR and H-1 NMR spectroscopy. Crystal structure determination
s revealed the complexes to be unsolvated monomeric metallocenes with
lanthanide centres co-ordinated by three cyclopentadienyl rings and tw
o oxygen atoms of the three 2-methoxyethyl moieties present; the third
oxygen is not co-ordinated. The distances Ln-C (eta(5)) and Ln-O(1) (
co ordinated oxygen) decrease as the ionic radius decreases; however,
Ln-O(3) (co-ordinated oxygen) increases.