The bis((2-methoxyethyl)cyclopentadienyl) rare earth metal chlorides (CH3OCH2CH2C5H4)2LnCl [Ln = La (1), Pr (2), Nd (3), Sm (4), Gd (5), Dy (6), Ho (7), Er (8), Tm (9), Yb (10), Lu (11), Y (12)] were synthesized by treating the respective rare earth metal trichlorides with 2 equiv of ((2-methoxyethyl)cyclopentadienyl)sodium in THF. The new compounds have been characterized by elemental analyses, MS, IR and NMR spectra, as well as X-ray diffraction analyses of 1, 6, and 10. 1 crystallizes from toluene in the monoclinic space group P2(1)/n (No. 14) with unit cell parameters a = 8.726(1) angstrom, b = 12.367(1) angstrom, c = 14.562(3) k, beta = 93.90(9)-degrees, and V = 1567.8(2) angstrom3 with Z = 4 for D(calcd) = 1.782 g cm-3 and R = 0.038 for 6771 independent reflections with [I > 3sigma(I)]. 6 and 10 crystallize from THF in the orthorhombic space group Pnma (No. 62) with unit cell parameters a = 12.242(3) angstrom, b = 11.723(6) angstrom, c = 11.293(2) angstrom, and V = 1620.7(2) angstrom3 with z = 4 for D(calcd) = 1.821 g cm-3 (6) and a = 12.207(4) angstrom, b = 11.705(3) angstrom, c = 11.176(2) angstrom, and V = 1596.8(6) angstrom3 with z = 4 for D(calcd) = 1.892 g cm-3 (10), respectively. Least-squares refinement led to a final R value of 0.027 for 1199 independent reflections [I > 3sigma(I)] for 6 and for 0.037 for 1118 independent reflections [I > 3sigma(I)] for 10. The X-ray structure analyses show that complex 1 is dimer and the formal coordination number of lanthanum is 10, but complexes 6 and 10 are monomeric; the formal coordination number of dysprosium and ytterbium is nine. It indicates that the molecular structure of those chlorides depends on the radius of central metal.