Synthesis and crystal structure of lanthanide sandwich complexes with mixed cyclooctatetraenyl and chelating ether side chain-cyclopentadienyl ligands: crystal structures of (eta(5)-MeOCH2CH2Cp)Nd(eta(8)-C8H8)(THF) and (eta(5)-C4H7OCH2C5H4)La(eta(8)-C8H8)(THF)

LnCl(3) reacted with K2C8H8 in THF in the ratio 1:1 at room temperature and formed (C8H8)LnCl . nTHF, which was then treated with RCpK-THF (RCp = MeOC H2CH2C5H4 or C4H7OCH2C5H4) to yield the title complexes (eta(5)-RCp)Ln(eta( 8)-C8H8) (THF) (Ln = Nd (1) and Sm (2), RCp = MeOCH2CH2C5H4; Ln = La (3), N d (4) and Sm (5), RCp = C4H7OCH2C5H4). The crystal structures of complexes 1 and 3 were determined by X-ray diffraction and revealed that the oxygen a toms of the ether group on the cyclopentadienyl ring is coordinated to the central metal atom. The central lanthanum atom is in a distorted tetrahedra l geometry. The average bond distances Nd-C(eta(8)) and Nd-C(eta(5)) are 2. 697(2) and 2.749(2) Angstrom, respectively, while the Nd-O(THF) and Nd-O(et a(1)) distances are 2.580(1) and 2.619(1) Angstrom, respectively. The avera ge bond lengths La-C(eta(5)) and La-C(eta(8)) are 2.842(7) and 2.740(8) Ang strom, respectively. The La-O(THF) and La-O(eta(1)) distances are 2.607(4) and 2.633(4) Angstrom. (C) 2000 Elsevier Science Ltd All rights reserved.