Lanthanide β-diketonate glyme complexes exhibiting unusual co-ordination modes

Abstract

The reaction of the hydrated β-diketonate complexes [Ln(tmhd)₃(H₂O)] with triglyme (2,5,8,11-tetraoxadodecane, L¹) in hexane yielded the eight-coordinate triglyme-bridged dimeric complexes, [{Ln(tmhd)₃}₂L¹](Ln = Eu 1 or Tb 2; tmhd = Bu^tCOCHCOBu^t). In contrast, the reaction of [La(tmhd)₃(H₂O)] with tetraglyme, (2,5,8,11,14-pentaoxapentadecane, L²) in hexane yielded the nine-co-ordinate monomeric compound [La(tmhd)₃L²]3, though with only three of the five possible oxygen atoms of the glyme utilized in bonding to the lanthanum. All of these complexes are air- and moisture-stable and most importantly have good volatility and thermal stability, as demonstrated by sublimation, differential scanning calorimetry and thermal gravimetic analysis. The structures of all three complexes have been determined by single-crystal X-ray diffraction.