ORGANOMETALLIC LANTHANOID COMPOUNDS .70. BIS(CYCLOPENTADIENYL)-RARE-EARTH COMPLEXES - SYNTHESIS AND X-RAY STRUCTURAL-ANALYSIS OF THE INTRAMOLECULARLY STABILIZED LUTETIUM ALKYL SPECIES CP2LU(CH2)3NME2 AND MONOMERIC BASE-FREE YTTRIUM CARBOXYLATE CP2Y[ETA-2-O2C(CH2)3NME2]

Metathesis of LuCl3, NaCp and Li(CH2)3NMe2 in the molar ratio 1:2:1 affords the lutetium alkyl species Cp2 activated Lu(CH2)3NMe2 (1); analogous reaction of LuCl3, NaMeC5H4 and LiCH2CH(Me)-CH2NMe2 generates the corresponding complex (MeC5H4)2 activated Lu[CH2CH(Me)CH2NMe2] (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 Cp2Y[eta(2)-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 P2(1) (No. 4) with the unit-cell parameters a 657.0(4), b 1386.7(8), c 803.5(3) pm, beta 106.64(5)-degrees, V 704(1) x 10(-30) m3 and Z = 2. The structure was solved on the basis of 1094 observed reflections with F(o) greater-than-or-equal-to 3-sigma(F(o)) 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 P1BAR (No. 2), with a 1078.2(6), b 1533.0(9), c 1020.3(8) pm, alpha-109.47(6), beta 82.75(6), gamma-88.99(5)-degrees, V 1574(2) x 10(-30) m3 and Z = 4. Least-squares refinement of the model based on 1659 observed reflections converged to R = 0.093 (F(o) greater-than-or-equal-to 5-sigma(F(o)). 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.