Synthesis and crystal structure of 1,1′-(3-oxapentamethylene)-bridged bis(indenyl) ansa-lanthanocene chlorides

Several representative chiral ansa-lanthanocene chlorides have been synthesized and characterised with a rac:meso ratio of 6:1 using an ether-bridged bis(indenyl) ligand. The structure of these complexes was identified by X-ray crystallography in the solid state or H-1 NMR spectroscopy in solution. The ligand proved to be rather rigid leading to the favoured unsymmetric rac isomer. The H-1 NMR spectra indicated that the configuration of the rac isomer in solution agrees well with that in the solid state and, interestingly, the two bridged indenyl rings of the rac isomers slowly oscillated.