Mean dipole-polarizability of of neodymium, samarium the tris(cyclopentadienides) and erbium, Nd(C5H5)(3), SM(C5H5)(3), and Er(C5H5)(3)

The frequency-dependence of the mean dipole-polarizability oc(a) of the org anometallic compounds Ln(C5H5)(3) (Ln = Nd, Sm, and Er) is studied by means of refractive index measurements in the vapour phase. From our white-light interferometric experiments the electronic static dipole-polarizabilities are obtained as alpha (0) = 367.7(2.8), 356.2(1.4), and 316.4(5.0) (in 10(- 41) C-2 m(2) J(-1)) in the sequence Nd, Sm, and Er. This result reflects th at an increase in the number of f-electrons in the series of the Ln(3+) ion s leads to a decrease in alpha (0). This observation is in good accordance with polarizabilities deduced from refractive indices and dielectric consta nts of the corresponding oxides and fluorides. However, it is opposite to w hat is found from studies of alpha(sigma) of these three compounds in tetra hydrofuran solution. (C) 2001 Elsevier Science BN. All rights reserved.