Tetraisopropylcyclopentadienyl chlorides of lanthanum, neodymium, and ytterbium

Bis(tetraisopropylcyclopentadienyl) chlorides of lanthanum (1) or neodymium (2) can be easily obtained in good yields from the respective trichlorides and sodium tetraisopropylcyclopentadienide. Both contain one equivalent of coordinated sodium chloride, for 2 a dimer [{(C5HR4)(2)Nd (mu -Cl)(mu (3)- Cl)Na(OEt2)}(2)] (R = CHMe2) with a folded sheet structure has been establ ished by X-ray crystal structure analysis. From sodium tetraisopropylcyclop entadienide and ytterbium trichloride or upon oxidation of octaisopropylytt erbocene with hexachloroethane the mono-ring complex [(C5HR4)YbCl2] (3) (R = CHMc(2)) has been obtained, which could be crystallographically character ized as monomeric dimethoxyethane adduct [(C5HR4)YbCl2(DME)].