Synthesis and crystal structure of lanthanide sandwich complexes with mixed cyclooctatetraenyl and chelating ether side chain-cyclopentadienyl ligands: crystal structures of (η5-MeOCH2CH2Cp)Nd(η8-C8H8)(THF) and (η5-C4H7OCH2C5H4)La(η8-C8H8)(THF)

Abstract

LnCl3 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=MeOCH2CH2C5H4 or C4H7OCH2C5H4) to yield the title complexes (η5-RCp)Ln(η8-C8H8)(THF) (Ln=Nd (1) and Sm (2), RCp=MeOCH2CH2C5H4; Ln=La (3), Nd (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 atoms of the ether group on the cyclopentadienyl ring is coordinated to the central metal atom. The central lanthanum atom is in a distorted tetrahedral geometry. The average bond distances Nd–C(η8) and Nd–C(η5) are 2.697(2) and 2.749(2) Å, respectively, while the Nd–O(THF) and Nd–O(η1) distances are 2.580(1) and 2.619(1) Å, respectively. The average bond lengths La–C(η5) and La–C(η8) are 2.842(7) and 2.740(8) Å, respectively. The La–O(THF) and La–O(η1) distances are 2.607(4) and 2.633(4) Å.