Thermochemical Properties (D degrees0 and IP) of the Lanthanide Monohalides.

Thermochemical data for the lanthanide monohalides have been combined with recent ligand field theory calculations (A. L. Kaledin, M. C. Heaven, R. W. Field, and L. A. Kaledin (1996). J. Mol. Spectrosc. 179, 310) to estimate the dissociation energies and ionization potentials for all LnX (where Ln in Ba through Lu, and X in F, Cl, Br, or I) molecules and the dissociation energies for the LnX+ ions. Owing to the negligible involvement of the core-like 4f electrons in bonding, the dissociation energies and ionization potentials of all LnX molecules, where Ln in Ba through Lu, and X in O, S, F, Cl, Br, or I, should vary with Ln atom in a simple linear manner, provided that corrections are made for differences in f-orbital occupancy between the LnX molecule and the free Ln atom or between the LnX molecule and the LnX+ molecular ion. We provide such a model here and, in so doing, correct several inconsistencies in the thermochemical data. Based on thermochemical data (A. A. Kitaev, I. S. Gotkis, P. G. Val'kov, and K. C. Krasnov (1996). Russ. Chem. Phys. 7, 1685) and recent spectroscopic observations (M. C. McCarthy, J. C. Bloch, R. W. Field, and L. A. Kaledin (1996) J. Mol. Spectrosc. 179, 251), a revised value for the ionization potential of DyF, IP(DyF) = 5.85 +/- 0.06 eV, is proposed. Copyright 1999 Academic Press.