Scandium(III) 1,1,1-Trifluorohexane-2,4-dionate Complex: Synthesis, Structure, and Thermal Properties
摘要
A new scandium(III) 1,1,1-trifluorohexane-2,4-dionate complex [Sc(5Htfac)3] was synthesized, purified, and characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. Its structure was determined at 150 K by X-ray diffraction analysis (CCDC no. 2433044). The complex has a molecular structure in which the bidentate cyclic ligands are arranged according to the os-isomer. Shortened H…F interactions were identified in the structure. The thermal properties were studied by TGA and DSC, and the fusion temperature (309.3 ± 0.5 K), enthalpy (ΔfusH°(Tfus) = 36.0 ± 1.4 kJ mol–1), and entropy (ΔfusS°(Tfus) = 116.5 ± 4.5 J mol–1 K–1) were determined. The temperature dependence of the saturated vapor pressure was measured by the flow method (343–433 K) and the static method with a membrane null manometer (410–470 K). On this basis, the thermodynamic characteristics of vaporization at average and standard temperatures were calculated (ΔvapH°(298.15 K) = 100.2 ± 1.3 kJ mol–1, ΔvapS°(298.15 K) = 201.8 ± 2.8 J mol–1 K–1). From these data, the sublimation parameters of the complex were obtained (ΔsubH°(298.15 K) = 135.3 ± 1.9 kJ mol–1, ΔsubS°(298.15 K) = 315.3 ± 5.4 J mol–1 K–1). The structure and thermal properties of [Sc(5Htfac)3] were compared with those of two scandium(III) β-diketonates bearing methyl and tert-butyl substituents in the ligand.