Synthesis and Thermodynamic Analysis of Volatile Beta-Diketone Complexes of Select Lanthanides via Gas-Phase Separations

Rapid separation techniques for fission and activation products have long been desired to supplant the slow solution-based methodologies currently used. In this work, rare earth elements were derivatized with β [beta]-diketones to synthesize rare earth complexes with high volatility suitable for gas-phase separations. Rare earth elements samarium and dysprosium were combined with hfac (1,1,1,5,5,5-hexafluoro-2,4-pentadione) and fod (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedione) and analyzed using a gas-phase separation technique. Rare earth elements praseodymium and europium were combined with dpm (2,2,6,6-tetra-methyl-3,5-heptanedione) and similarly analyzed. Employing the data from the separations, the entropy (Δ [delta] S) and enthalpy (Δ [delta] H) of adsorption were evaluated mathematically based on compound retention within the thermochromatographic test apparatus. New thermodynamic values for enthalpy and entropy of adsorption were calculated as -1±3 kJ/mol and -49±8 J/mol*K for Sm[hfac], 31±8 kJ/mol and 26±16 J/mol*K for Dy[hfac], -20±40 kJ/mol and -94±94 J/mol*K for Sm[fod], 27±4 kJ/mol and 21±10 J/mol*K for Dy[fod], -24±2 kJ/mol and -98±5 J/mol*K for Pr[dpm], and -12±0 kJ/mol and -68±0 J/mol*K for Eu[dpm].