Synthesis and X-ray crystal structure of [Eu(η6-C6Me6)(AlCl4)2]4; the first cyclotetrameric lanthanide(II) complex with a neutral π-ligand

Abstract
The reaction of EuCl3, AlCl3 and C6Me6 in toluene gives the EuII complex [Eu(η6-C6Me6)(AlCl4)2]4; X-ray crystal determination shows the molecule to be a cyclotetramer, in which the four Eu(C6Me6)AlCl4 units are connected via four groups of η2-AlCl4.