The electronic absorption spectra of vapor-phase compounds formed by reacting SmCl3(s) and SmCl2(s) with gaseous A12C16 have been measured at temperatures up to 800 K and total pressures up to 13 atm. The spectra of the pale yellow Smln-Al-Cl gaseous complex(es) were characteristic of the f -»-f electronic transitions of Sm(III). The spectra of the red-brown SmIL-Al-Cl gaseous complex(es) showed high-intensity, broad bands which are attributed to 4f -*• 5d transitions of Sm(II). Spectrophotometric measurements have been used to investigate the partial pressures of the vapor complexes at different A12C16 pressures. Thermodynamic considerations suggest that the SmAl3Cl12 is the predominant vapor species formed by the trivalent samarium. For the reaction SmCl3(s) + 3/2Al2Cl6(g) -SmAl3Cl12(g) the values of AH = 6.7 kcal/mol and 5 = -1.0 eu have been derived. At 650 K the volatility enhancement of Sm(II) has been estimated to be ~10 . Rare earth oxides have been halogenated and vapor transported using A12C16 or Al2Br6. A new method for the preparation of anhydrous rare earth halide crystals is suggested. The data are discussed in terms of the systematics of formation and structure of gaseous lanthanide chloride complexes.

The thermal conductivity of methanol vapor was measured in a modified thick hot-wire cell between 307 and 345 K at pressures ranging from approximately 50 torr up to a maximum of 1 atm. Analysis of the experimental data indicates that a tetrameric species is the principal source of the observed enhancement of the thermal conductivity of the vapor due to association reactions. Equilibrium constants for the reaction 4CH3OH? (CH3OH)4 were determined from the thermal conductivity data. The enthalpy of formation of the methanol tetramer is −23.73 kcal/mole and the entropy of formation is −80.92 cal/mole K.

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