Thermodynamic Study of the Phase Transitions of (Pivaloyltrifluoroacetonato)cyclooctadiene-1,5) Iridium

New data are obtained on the thermal behavior and sublimation and melting of (pivaloyltrifluoroacetonato)(cyclooctadiene-1,5)iridium {[Ir(cod)(ptac)]}. The condensed phase is studied via differential scanning calorimetry, and the complex’s temperature of melting is determined along with its enthalpy and entropy of fusion: Tmelt = 405.9 ± 0.5 K; $${{\Delta }_{{{\text{fus}}}}}H_{{\text{m}}}^{^\circ }$$ (Tmelt) = 20.4 ± 0.3 kJ mol−1; $${{\Delta }_{{{\text{fus}}}}}S_{{\text{m}}}^{^\circ }$$ ; (Tmelt) = 50.3 ± 0.7 J mol−1 K−1. The temperature dependence of the saturated vapor pressure of [Ir(cod)(ptac)] in the 363–397 K range of temperatures is obtained from the flow. The thermodynamic characteristics of sublimation are calculated at the average temperature of the experimental range and 298.15 K: $${{\Delta }_{{{\text{subl}}}}}H_{{\text{m}}}^{^\circ }$$ (Tav) = 102.0 ± 1.8 kJ mol−1; $${{\Delta }_{{{\text{subl}}}}}S_{{\text{m}}}^{^\circ }$$ (Tav) = 188.5 ± 3.3 J mol−1 K−1; $${{\Delta }_{{{\text{subl}}}}}H_{{\text{m}}}^{^\circ }$$ (298.15 K) = 107.3 ± 2.9 kJ mol−1; and $${{\Delta }_{{{\text{subl}}}}}S_{{\text{m}}}^{^\circ }$$ (298.15 K) = 204.1 ± 5.7 J mol−1 K−1. The resulting values are compared to those of similar compounds of iridium(I) and other β-diketones, [Ir(cod)(β-dik)]. The results form the basis for developing a way of assessing the thermodynamic properties of complexes [M(cod)(β-dik)], which is needed when compounds (e.g., [Ag(cod)(β-dik)]) are hypersensitive to heating and it is impossible to determine reliable thermodynamic characteristics experimentally in order to establish the optimum conditions for the gas-phase deposition of etal-containing coatings.