Complex of Magnesium Octafluoropropionyl Acetonate with N,N,N',N'-Tetramethylethylenediamine, [Mg(tmeda)(ofhac)₂]: A Potential Volatile Precursor of MgF₂ Films

Mixed-ligand complexes of magnesium with fluorinated β-diketones and diamines are promising as precursors for the preparation of thin MgF₂ films by metal-organic chemical vapor deposition (MOCVD). The currently most volatile representative of this family, [Mg(tmeda)(ofhac)₂] (tmeda = (CH₃)₂NCH₂CH₂CN(CH₃)₂, ofhac = C₂F₅COCHCOCF \(_{3}^{ - }\) ), was studied. The melting process was characterized by DSC (T_m = 354.4 ± 0.6 K, ∆_mH = 23.3 ± 0.9 kJ/mol). The complex was shown to be stable in the condensed phase up to at least 473 K. The temperature dependence of the heat capacity was studied in the range 298–403 K (DSC, using sapphire as a standard). The temperature dependences of the saturated vapor pressure over the solid (318–352 K) and liquid (358–393 K) complex were measured by transport in a helium flow. The thermodynamic parameters of sublimation and vaporization were determined. The possible isomers of the complex (based on the position of the C₂F₅ substituents) were compared using quantum-chemical calculations (B3LYP-D3(BJ)/def2-SVP, def2-TZVP, and OPBE/TZ2P-J).