Résumé
Three new unsolvated organometallic complexes of dysprosium(III) with very sterically hindered pi-ligands have been synthesized and structurally characterised: the monomeric bis[eta(5)-(1,2,4-tris-trimethylsilylcyclopentadienyl)]iododysprosium (1b), bis[eta(5)-(1,4-bis-t-butyl-2,3-dimethylphospholyl)]iododysprosium, (1c) and the dimeric tetraikis[eta(5)-(1,4-bis-t-butyl-2,3-dimethylphospholyl)]bis (mu-iodo)di-dysprosium (1d). The relative steric bulk of the pi-ligands have been assessed by comparison of the structural data of 1b-d with that of the previously described bis[eta(5)-(1,2.4-tris-t-butylcyclopentadienyl)]iododysprosium (1a). Contrary to la, reduction attempts on 1b-d were unsuccessful. The reaction of the dysprosium(II) complex bis[eta(5)-(1,2.4-tris-t-butylcyclopentadienyl)]dysprosium (mu-bromo)-potassium[18]crown-6 (3) with fluorenone resulted in its monoelectronic reduction and coordination of the resulting ketyl to dysprosium(III): isolation of potassium[18]crown-6 bis[eta(5)(1 2,4-trist-butylcyclo-pentadienyl)](fluorenone ketyl)bromodysprosate (4) that was structurally characterised. (C) 2009 Elsevier Ltd. All rights reserved.