MOSSBAUER-EFFECT STUDIES OF A NEW ORGANOEUROPIUM COMPLEX [EU(ETA-6-C6ME6)(ALCL4)2]4

The Mossbauer spectrum of a new organoeuropium complex with a neutral pi-ligand, Eu(eta6-C6Me6) (AlCl4)2, is measured at 88 K. The Mossbauer parameters derived from the spectrum show the divalent nature of the europium ion in this organoeuropium complex. The calculations of the e lectric field gradient at the Eu nucleus in the crystal indicate that the Eu-Cl bond in the compound may possess a certain covalent characte r. The low Debye temperature of this complex may be attributed to weak and delocalized pi-bonding between the Eu atom and the benzene ring o f hexamethylbenzene, and a slow paramagnetic relaxation is suggested b y the Mossbauer effect.