VAPOR-PRESSURES AND STANDARD MOLAR ENTHALPY OF SUBLIMATION OF CRYSTALLINE TRIS(PENTANE-2,4-DIONATO)RUTHENIUM(III)

The Knudsen mass loss effusion technique was used to measure the vapou r pressure of crystalline tris(pentane-2,4-dionato)ruthenium(III) as a function of temperature between 398.18 and 413.15 K using three diffe rent effusion holes. From the temperature dependence of the vapour pre ssure, the standard molar enthalpy of sublimation at the mean temperat ure of the experimental temperature range, 405.7 K, was derived as 139 .7 +/- 2.5 kJ mol-1. Using an estimated value of DELTA(cr)gC(p)o = -50 J K-1 mol-1, the standard molar enthalpy of sublimation at 298.15 K w as calculated as 145.1 +/- 2.5 kJ mol-1.