Synthesis, Structure, and Thermal Properties of Scandium(III) and Iron(III) Complexes with 3-Methyl-2,4-Pentanedione as Precursors for Chemical Gas-Phase Processes

Abstract

Complexes Sc(Meacac)3 and Fe(Meacac)3 (Meacac is 3-methyl-2,4-pentanedionate anion) have been synthesized, and their crystal structures have been first determined by X-ray diffraction. The volatility and thermal stability of the obtained compounds have been studied. The temperature, enthalpy, and entropy of melting of the complexes have been determined by differential scanning calorimetry. The flow method has been used to obtain the temperature dependence of the saturated vapor pressure of Sc(Meacac)3 in the range 414–472 K, from which the thermodynamic characteristics of the sublimation process have been calculated at an average temperature (= 132.8 ± 1.8 kJ/mol,= 226.1 ± 4.6 J/(K mol)) and at 298.15 K (= 143.9 ± 2.6 kJ/mol,= 256.5 ± 6.4 J/(K mol)). The compounds studied can be used as precursors in chemical vapor deposition, and the set of obtained thermodynamic data can be used to select the optimal deposition conditions.