Synthesis and X-ray structures of trivalent lanthanide (+)-neomenthylcyclopentadienyl complexes

Trivalent lanthanide (+)-neomenthylcyclopentadienyl complexes [Cp(2)(R)Ln(m u-Cl)](2) (Ln = Sm (1), Yb (2), Y (3), Lu (4); Cp-R = (+)-neomenthylcyclope ntadienyl)] and Cp(R)LnX(2)(THF)(3) [X = Cl, Ln = Sm (6), Gd (7), Yb (8), Y (9), Lu (10); X = I, Ln = Sm (11), Yb (12)) have been prepared by metathet ical reactions of lanthanide halide with appropriate alkali-metal (+)-neome nthylcyclopentadienyl complexes. X-ray structural analysis has revealed tha t compounds 1 and 3 are chloro-bridged dimers with the asymmetric plane des cribed by Ln(2)Cl(2) almost perpendicular to the plane described by the fou r cyclopentadienyl ring centroids. The monomeric compound Cp(R)LnI(2)(THF)( 3) (11) adopts a pseudo-octahedral geometry with the two iodine atoms takin g the trans-positions. (C) 1999 Elsevier Science S.A. All rights reserved.