Ether-Functionalized Organoamide Coordination to Lanthanoid(II)/(III) Centres

Ligand exchange reactions of [Ln{N(SiMe3)(2)}(2)(S)(x)] (Ln = Eu, (S)(x) = (thf)(2) or dme; Ln = Yb, (S)(x) = dme) (where thf and dme represent tetrahydrofuran and 1,2-dimethoxyethane, respectively) with N-2-(methoxyphenyl)-N-trimethylsilylamine ((LH)-H-1) in toluene at low temperatures yielded thermally unstable [Ln(L-1)(2)(S)x] (Ln = Eu, (S) x = (thf)(2) or dme; Ln = Yb, (S)(x) = dme). An analogous reaction with N-2-(phenoxyphenyl)-N-trimethylsilylamine ((LH)-H-2) and[Yb{N(SiMe3)(2)}(2)(thf)(2)] did not give the expected lanthanoid(II) complex but instead gave [Yb(L-2)(2)(OPh)(thf)]. The three lanthanoid(II) complexes exhibit monomeric, distorted cis-octahedral structures and have two chelating amide (L-1) ligands with a further one dme or two thf molecules required to saturate the metal coordination sphere. Oxidation of [Yb(L-1)(2)(thf)(2)] with TlCp gave thallium metal and the ytterbium(III) complex [YbCp2(L-1)], presumably formed by ligand redistribution of a Yb(L-1)(2) Cp species. The reaction of [YbCp*(2)(thf)] (where Cp* represents C5Me5) with new Hg(L-1)(2) or Hg(L-2)(2) compounds generated mercury metal and the bis(pentamethylcyclopentadienyl)ytterbium( III) complexes [YbCp*(2) (L-1)] and [YbCp*(2) (L-2)]. The three cyclopentadienylytterbium(III) complexes are monomeric and adopt classical eight-coordinate, pseudo-tetrahedral geometries derived from two eta (5)-Cp or Cp* ligands and a chelating L-1 or L-2 amide.