SYNTHESIS, FLUXIONAL BEHAVIOR IN SOLUTION AND CRYSTAL-STRUCTURE OF THE ORGANOLANTHANIDE COMPLEXES [LN(C5H4CH2CH2OME)2(THF)][CO(CO)4] (LN = SM OR YB, THF = TETRAHYDROFURAN)

The [Ln(C5H4CH2CHOMe)2(thf)]+ cations (Ln = Sm 1 or Yb 2, thf = tetrahydrofuran) which represent the first examples of organolanthanide cationic complexes with [Co(CO)4]- as anion, have been synthesised by metathesis of [Ln(C5H4CH2CH2OMe)2I] with K[Co(CO)4] or by one-electron oxidation of divalent [Ln(C5H4CH2CH2OMe)2(thf)] with [Co2(CO)8]. The crystal structure of complex 2 has been determined: space group P2(1)2(1)2, a = 10.700(3), b = 11.509(4), c = 10.381(4) angstrom, Z = 2. Least-squares refinement led to convergence with R = 0.040, R' = 0.047. It exists as discrete cations and anions with no Ln-OC-Co linkage. The samarium analogue 1 is isostructural. Variable-temperature NMR studies indicated that, at low temperature, the spectra of complex 1 are in good accordance with the structure in the solid state. At high temperature the two ether chains of 2 remain co-ordinated on the metal.