Metallorganische verbindungen der lanthanoide : LXX. Bis(cyclopentadienyl)seltenerdkomplexe: Synthese und röntgen-strukturanalyse von dem intramolekular stabilisierten lutetiumalkyl Cp2 Me2 und dem monomeren basenfreien yttriumcarboxylat Cp2Y[η-O2C(CH2)3NMe2]

Metathesis of LuCl₃, NaCp and Li(CH₂)₃NMe₂ in the molar ratio 1:2:1 affords the lutetium alkyl species Cp₂ Me₂ (1); analogous reaction of LuCl₃, NaMeC₅H₄ and LiCH₂CH(Me)-CH₂NMe₂ generates the corresponding complex (MeC₅H₄)₂ Me₂] (2). Treatment of YCl₃ with two equivalents of NaCp and one equivalent of Li(CH)₃NMe₂ yields, in the presence of CO₂, the yttrium carboxylate Cp₂Yη²-O₂C(CH₂)₃NMe₂ (3). Mass spectrometrical studies of the solvent-free rare earth triflates Cp₂Ln(OSO₂CF₃)]₂ (Ln = Sc (4), Lu (5)) have shown them to be dimeric. The crystal structures of 1 and 3 were determined by X-ray diffraction methods. 1 crystallizes in the monoclinic space group P2₁ (No. 4) with the unit-cell parameters a 657.0(4), b 1386.7(8), c 803.5(3) pm, β 106.64(5)°, V 704(1) × 10⁻³⁰ m³ and Z = 2. The structure was solved on the basis of 1094 observed reflections with F₀ ≥ 3σ(F₀) and refined to a final R value of 0.0483. With the short Lu---N bond length of 237(1) pm the molecular structure of 1 exhibits an intramolecular N → Lu coordination. The crystals of 3 are triclinic, space group P (No. 2), with a 1078.2(6), b 1533.0(9), c 1020.3(8) pm, α 109.47(6), β 82.75(6), γ 88.99(5)°, V 1574(2)×10⁻³⁰ m³ and Z = 4. Least-squares refinement of the model based on 1659 observed reflections converged to R = 0.093 (F₀ ≥ 5σ(F₀)). The structural data of 3 feature a monomer with a chelating carboxylate group. The long Y---N distance (499 pm) excludes any intramolecular N---Y interactions.