Thermochemistry of Heteroatomic Compounds. Enthalpy of Dissolution and Vaporization of Selected Trimethylsilyl Di- and Tetrathiophosphates

Resumo

Enthalpy of vaporization (Δ_vapH°) of trimethylsilyl esters of dithio- and tetratiophosphoric acids (RX)₂P(S)SSiMe₃ (X = O, S) have been determined from the experimentally determined enthalpies of their dissolution (Δ_dissH°) in n-hexane at 296–298 K and the values of molar refraction (MR_D) with correction a for the branching of the carbon substituent according to the equation Δ_vapH° = Δ_dH°(n-hexane) + 4.39 + 1.05(MR_D − α). The obtained vaporization values can be used to calculate the heats of formation of similar, thermally unstable, compounds for experimental calorimetry.