LANTHANIDE BETA-DIKETONATE GLYME COMPLEXES EXHIBITING UNUSUAL COORDINATION MODES

The reaction of the hydrated beta-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(t)COCHCOBu(t)). In contrast, the reactio n of [La(tmhd)3(H2O)] with tetraglyme (2,5,8,11,14-pentaoxapentadecane , L2) in hexane yielded the nine-co-ordinate monomeric compound [La(tm hd)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 volatilit y and thermal stability, as demonstrated by sublimation, differential scanning calorimetry and thermal gravimetic analysis. The structures o f all three complexes have been determined by single-crystal X-ray dif fraction.