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Mass spectrometric and quantum chemical studies of the thermodynamics and bonding of neutral and ionized LnCl, LnCl(2), and LnCl(3) species (Ln = Ce, Lu).

Saloni J, Roszak S, Hilpert K, Popovic A, Miller M, Leszczynski J

Computational Center for Molecular Structure and Interactions, Jackson State University, Jackson, Mississippi 39217, USA.

The mass spectral patterns of CeCl(3)(g) and LuCl(3)(g) and appearance energies for the identified ions were measured using a Nier-type mass spectrometer coupled with a Knudsen cell. The molecular ion CeCl(3)(+) was found to be considerably less stable in comparison to LuCl(3)(+). Partial pressures and sublimation enthalpies of LnCl(3)(s) to monomeric LnCl(3)(g) and dimeric Ln(2)Cl(6)(g) species were obtained in the ranges of 882-1028 (Ln = Ce) and 850-1004 K (Ln = Lu). The contribution of dimeric Ce(2)Cl(6)(g) species to equilibrium vapors of CeCl(3)(s) is considerably smaller than the Lu(2)Cl(6)(g) contribution in LuCl(3)(s) vapors. The measurements were supplemented by quantum chemical ab initio studies of structures, energetics, and vibrational frequencies of neutral and singly ionized LnCl, LnCl(2), and LnCl(3) species (Ln = Ce, Lu). The theoretical appearance energies of different ions, calculated from the energies of the gaseous species, are in good agreement with experimental data. The fragmentation energies of LnCl, LnCl(2), and LnCl(3) were also computed and compared with the mass spectral patterns of respective vapor species. The Mulliken and natural bond orbital electron population methods were applied for the systematic analysis of the bonding scheme in molecules and cations.

Published 22 May 2006 in Inorg Chem, 45(11): 4508-17.
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