The complexes, (C5H5)3M(py) (M = Nd, Sm, Eu or Yb), (C5H5)2Eu(py), and (C5H5)2Yb(py)2 have been prepared from the appropriate lanthanoid elements and thallous cyclopentadienide in pyridine, and (C5H5)3M(NCMe) (M = Nd, Sm or Yb) and (C5H5)2Yb(NCMe) from similar reactions in acetonitrile. Ligand exchange or addition has also been used to give (C5H5)3 Sm(py), (C5H5)2Yb(py)2 and (C5H5)2Yb(NCMe). Ytterbium metal reduces (C5H5)3Yb(py) in pyridine to (C5H5)2Yb(py)2, which is oxidized back to (C5H5)3Yb(py) by T1(C5H5). Europium with (C5H5)2Hg in tetrahydrofuran yields (C5H5)3Eu(thf), and (C5H5)2Eu is not isolated by using an excess of metal. Oxidation of (C5H5)2Eu to (C5H5)3Eu is effected by (C5H5)Hg in tetrahydrofuran but not by T1(C5H5) in 1, 2-dimethoxyethane. Europium and ytterbium react with bis(pentafluorophenyl)mercury and cyclopentadiene in pyridine to give (C5H5)3M(py) (M = Eu or Yb).