Thermochemical study of volatile heteroligand magnesium complexes with 2,2,6,6-tetramethylheptane-3,5-dione and aromatic diamines

Abstract

Two heteroligand volatile magnesium(II) β-diketonate complexes with 2,2′-bipyridine [Mg(bipy)(thd)2] and 1,10-phenanthroline [Mg(phen)(thd)2], CASRN 182566-25-2, (thd = 2,2,6,6-tetramethylheptane-3,5-dionate-anion) have been synthesized. The compounds have been purified and properly characterized to investigate further their sublimation and melting processes. Their vapor pressures have been measured by using the flow method for the first time. Based on these data, thermodynamic characteristics of enthalpy and entropy of sublimation have been calculated at the average temperature of the experimental range. Condensed phase thermal behavior up to melting has been studied by differential scanning calorimetry and the corresponding thermodynamic characteristics have been determined. Data on sublimation has been processed in order to adjust the values of enthalpy and entropy of the processes at the reference temperature of 298.15 K. Whole set of a new thermochemical data could serve as a base for definition of optimal evaporator temperature regimes in chemical vapor deposition of MgO films using [Mg(bipy)(thd)2] and [Mg(phen)(thd)2] as precursors.