Transformation of the bis(trimethylsilyl)methyl into the 1-aza-allyl and beta-diketiminato ligands .7. Synthesis, characterisation and alkylation reactions of lanthanide beta-diketiminates; Crystal structures of [Nd(L-L)(2)Cl] and[Ce(L-L)(CHR2)(2)] [L-L=N(R)C(Ph)C(H)C(Ph)NR, R=SiMe3]

Treatment of two equivalents of the sodium beta-diketiminate Na(L-L) 1 with a lanthanide metal(III) chloride, LnCl(3), yielded the mononuclear complex [Ln(L-L)(2)Cl] (Ln = Ce 3, Pr, Nd 5, Sm or Yb); similarly two equivalents of 1 with TmI3 gave [Tm(L-L)(2)I] [L-L = N(R)C(Ph)C(H)C(Ph)NR; R = SiMe3]. When 3 was mixed with either one or two equivalents of Li(CHR2) in diethyl ether, the only new cerium-contaning product was [Ce(L-L)(CHR2)(2)] 9. Lanthanide metal(III) beta-diketiminates [Ln(L-L)(2)(thf)(2)] (Ln = Sm or Yb) or [Yb(L-L)(2)] and [Yb(L-L')(2)] 13 were obtained from [LnI(2)(thf)(2)] (Ln = Sm or Yb) and K(L-L) in thf, or YbI2 and K(L-L) or K(L-L') in Et2O [L-L' = N(R)C(Ph)C(H)C(Bu-t)NR; thf = tetrahydrofuran]. The various lanthanide metal beta-diketiminates were characterised by elemental analysis, mass spectrometry and multinuclear NMR spectra. The last of these indicated (by variable-temperature experiments) that for [Yb(L-L')(2)] 13 two isomers were present. X-Ray diffraction data for [NdL-L)(2)Cl] 5 and [Ce(L-L)(CHR2)(2)] 9 revealed that for each of these crystalline mononuclear complexes the metal atom is well shielded, due to the extremely sterically demanding monoanionic [L-L](-) ligand, which has some eta(5) character in these molecules.