SYNTHESIS AND CRYSTAL-STRUCTURES OF TRIS(2-METHOXYETHYLCYCLOPENTADIENYL)LANTHANIDE COMPLEXES

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.