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

Abstract

Ligand exchange reactions of [Ln{N(SiMe₃)₂}2(_S)_x] (Ln = Eu, (S)_x] = (thf)₂or dme; Ln = Yb, (S)_x = dme) (where thf and dme represent tetrahydrofuran and 1,2-dimethoxyethane, respectively) with N-2- (methoxyphenyl)-N-trimethylsilylamine (L¹H) in toluene at low temperatures yielded thermally unstable [Ln(L¹)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 (L²H) and [Yb{N(SiMe₃)₂}₂}(thf)₂}] did not give the expected lanthanoid(II) complex but instead gave [Yb(L²)₂}(OPh)(thf)]. The three lanthanoid(II) complexes exhibit monomeric, distortedcis-octahedral structures and have two chelating amide (L¹) ligands with a further one dme or two thf molecules required to saturate the metal coordination sphere. Oxidation of [Yb(L¹)₂(thf)₂] with TlCp gave thallium metal and the ytterbium(III) complex [YbCp₂(L¹)], presumably formed by ligand redistribution of a Yb(L¹)₂Cp species. The reaction of [YbCp* ₂(thf)] (where Cp* represents C₅Me₅) with new Hg(L¹)₂or Hg(L²)₂ compounds generated mercury metal and the bis(pentamethylcyclopentadienyl)ytterbium(III) complexes [YbCp*₂(L¹)] and [YbCp* ₂(L²)]. The three cyclopentadienylytterbium(III) complexes are monomeric and adopt classical eight-coordinate, pseudo-tetrahedral geometries derived from two η⁵-Cp or Cp* ligands and a chelating L¹ or L² amide.