Vapor pressure of tetrakis(1,1,1-trifluro-5,6-dimethylheptanedionato)zirconium(IV) and dichlorobis(η5-cyclopentadienyl)zirconium(IV) by TG-based transpiration technique

Zr(tfpm)4 (tfpm = 1,1,1-trifluro-5,6-dimethylheptanedionate) (1), was prepared and characterized by FT-IR, FABMS (Mol.Wt. = 869) and TG–DTA analyses. The TG–DTA curve exhibited a single step volatilization commencing from its melting point of 121 °C and volatilizes with a nil residue at 210 °C; ZrCp2Cl2 (2) melts at 241 °C and it completely volatile at 310 °C leaving nil residue. The equilibrium vapor pressure of (1) and (2) over the range of 121.4–152 °C and 135.4–176 °C were determined to be log(pe/mPa) = 12 ± 1 − 3700 ± 260/T (°C) and log(pe/mPa) = 13.1 ± 0.1 − 4533 ± 40/T (°C), respectively by employing a TG-based transpiration technique. The enthalpies of vaporization (ΔH°vap) for (1) and (2) as calculated from the slope of the curve were found to be 71 ± 5 and 87 ± 1 kJ mol−1, respectively. The entropies of vaporization (ΔS°vap) for (1) and (2) as calculated by using Trouton’s rule were found to be 180.2 ± 13 and 169.3 ± 0.2 J mol−1 K−1, respectively.