Thermodynamics of vaporization of the mixed-ligand complex of sodium dipivaloylmethanate with o-phenanthroline Na(thd)(phen)

Abstract

Vaporization of the complex between sodium dipivaloylmethanate and o-phenanthroline Na(thd)(phen) is studied using the Knudsen effusion method and mass spectral analysis of the gas-phase composition. Sublimation of the compound is found to occur congruently. Saturated vapor predominantly consists of o-phenanthroline molecules C₁₂H₈N₂, trimeric molecules Na₃(thd)₃, and a minor amount of Na₄(thd)₄ and Na(thd)(phen) molecules. The absolute partial pressures and enthalpies of sublimation of the gas-phase components, as well as the Δ_fG⁰(T) of formation of the complex from Na(thd)(s) and Phen(l), are calculated. The standard enthalpy of dissociation of gaseous Na(thd)(phen) into Na₃(thd)₃(g) and Phen(g) is estimated.