Vapor species over cerium and samarium trichlorides, enthalpies of formation of (LnCl₃)_n molecules and Cl⁻(LnCl₃)_n ions

Abstract

A Knudsen effusion cell mass spectrometric technique was used to study vapor species over CeCl(3) and SmCl(3). Monomer, dimer, and trimer (Sm(3)Cl(9)) molecules, and LnCl(4-), Ln(2)Cl(7-), Ln(3)Cl(10-) (Ln = Ce, Sm) negative ions, were observed in saturated vapor in the temperature range 958-1227 K. Partial vapor pressures of neutral constituents were determined and the enthalpies of sublimation (Delta(s)H, 298 K, kJ.mol(-1)) to monomers and associated molecules obtained: 328 +/- 6 (CeCl(3)), 306 +/- 6 (SmCl(3)), 453 +/- 16 (Ce(2)Cl(6)), 408 +/- 12 (Sm(2)Cl(6)), and 468 +/- 40 (Sm(3)Cl(9)). Equilibrium constants for various chemical reactions were measured and the enthalpies of reactions obtained using the second and third laws of thermodynamics. The enthalpies of formation (Delta(f)H, 298 K, kJ.mol(-1)) of molecules and ions have been calculated as follows: -730 +/- 6 (CeCl(3)), -722 +/- 6 (SmCl(3)), -1663 +/- 16 (Ce(2)Cl(6)), -1649 +/- 13 (Sm(2)Cl(6)), -2617 +/- 40 (Sm(3)Cl(9)), -1250 +/- 15 (CeCl(4)(-)), -1252 +/- 15 (SmCl(4-)), -2184 +/- 35(Ce(2)Cl(7-)), -2172 +/- 26 (Sm(2)Cl(7-)), -3183 +/- 43 (Ce(3)Cl(10-)), and -3147 +/- 43 (Sm(3)Cl(10-)).

The Composition of Saturated Vapor over 1-Butyl-3-methylimidazolium Tetrafluoroborate Ionic Liquid: A Multi-Technique Study of the Vaporization Process

“…Therefore, one can conclude that imidazole-2-ylidene is the main molecular precursor of these ions. Ylidene has no ionic bond and its ionization mechanism is close to those of inorganic polyhalides (see [55]) where the intensity of the molecular ion is less (or absent at all) than that of the first dissociative ion. That is why there is no molecular ion with m/z = 206, but the ion with m/z = 187 is present in the mass spectrum.…”

A Neoteric Neodymium Model: Ground and Excited Electronic State Analysis of NdF2+

“…Thermodynamic properties for many of the trihalides also have been measured. Enthalpies of formation for LnX 3 (X = Cl, Br, I) are known in the solid state, and the enthalpies of formation also have been measured for many of the trichlorides in the gas phase. − Lanthanide fluorides are less thoroughly studied, although the bond dissociation energies of NdF 3 , NdF 2 , and NdF have been measured via Knudsen effusion cell mass spectroscopy …”

Mass Spectrometric and Quantum Chemical Studies of the Thermodynamics and Bonding of Neutral and Ionized LnCl, LnCl2, and LnCl3 Species (Ln = Ce, Lu)

“…The vaporization of cerium and lutetium chlorides was studied by applying different experimental approaches. The discussion and critical assessment of data for CeCl 3 was given previously. − Pogrebnoi et al have studied the vaporization of LuCl 3 by the Knudsen effusion mass spectrometry technique, and they have also supplied a comparison with previously published results. The vapors of CeCl 3 and LuCl 3 are predominantly monomeric, although mass spectrometric studies show evidence for dimeric species of cerium chloride 12,13 and oligomers, up to tetramers, for lutetium chloride .…”

“…The vapors of CeCl 3 and LuCl 3 are predominantly monomeric, although mass spectrometric studies show evidence for dimeric species of cerium chloride 12,13 and oligomers, up to tetramers, for lutetium chloride . The ionic−molecular equlibria were investigated in cerium chloride and lutetium chloride vapors as well. , Several experimental and quantum chemical studies were carried out on the molecular structure of monomeric LnCl 3 species and are discussed in the recent reviews of Hargittai and Kovacs and Konings …”