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Crystal structure, thermal stability, and the process of scandium tris-methylcyclopentadienyl Sc(MeCp)3 evaporation are studied. It is shown by XRD that crystals of this compound with the C2/c space group and the following parameters at 150 K are formed from the gas phase and from the solution: a = 7.9568(4) Å, b = 13.7620(6) Å, c = 28.239(2) Å, β = 107.4860(10)°, V = 2949.3(3) Å3, Z = 8, Dcalc = 1.217 g/cm3. The violation of the crystal packing order is manifested as diffuse scattering accompanied by single-crystal Bragg diffraction. The obtained data suggest that the complex has the Sc(η5-MeCp)2(η1-MeCp) structure with Sc–Z distances equal to 2.26-2.37 Å, where Z is the center of the η5-MeCp species or the C atom (for η1-MeCp). The NMR data obtained for the Sc(MeCp)3 samples, which were kept for 7 days at 423 K, 453 K, and 483 K, indicate that the substance undergoes noticeable decomposition only at the highest temperature. Temperature dependences of the saturated vapor pressure of the complex are measured independently by the flow method (transpiration) (392-469 K) and by the static method (441-514 K). As a result of joint processing of the tensimetry data, the following thermodynamic parameters of Sc(MeCp)3 evaporation are determined: ΔevH0(458.5) = 82.5±1.1 kJ/mol, ΔevS0(458.5) = 135±2 J/(mol·K). [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermal properties of two new volatile fluorinated scandium(III) β-diketonates were studied. • Saturated vapor pressures were measured by the transpiration method. • TG-DTA and DSC analysis were carried out. • Standard molar enthalpies and entropies of sublimation, vaporization and fusion were derived. • Effect of fluorine introduction on thermal properties of the compounds was established. Scandium complexes with β-diketonate ligands are valuable precursors for the metal–organic chemical vapour deposition (MOCVD) of scandia based materials. The technology has been constantly developing and demanding novel precursors with accurately defined thermal properties, which could be used in MOCVD as well as related gas phase processes. Two new complexes with 1,1-difluoroacetylacetone (dfac) and 5,5,6,6,6-pentafluorohexane-2,4-dione (5Fac) have been synthesized, isolated, and characterized. The volatility and condensed phase behaviour including thermal stability and phase transitions of the obtained compounds have been studied; the saturated vapour pressures over crystalline Sc(dfac) 3 and liquid Sc(5Fac) 3 complexes have been measured. As a result, the standard molar thermodynamic characteristics of melting, sublimation, and vaporization processes have been calculated. Thermal properties of these compounds have been compared with literature data on scandium(III) β-diketonates already used as MOCVD precursor. These new compounds can be successfully used as precursors in the gas-phase deposition processes, and the set of obtained thermodynamic data can help in choosing the optimal deposition conditions. [ABSTRACT FROM AUTHOR]