Protonation, complexation and thermochemical behaviour of N-benzoylthiocarbamic-O-alkylester anions in solution

Enthalpies of protonation and metal complex formation of anions of a series of five N-benzoylthiocarbamic-O-alkylesters (R=Et, i-Pr, n-Bu, n-Hex, n-Dodec; 1–5) have been measured by titration calorimetry. Using known stability constants the reaction entropies have been calculated. The free ligands HL are verified to react as NH-acids. The remarkable gain of entropy mainly depends on the high number of lost molecules from the extended solvation shell of the reacting species in the 1,4-dioxane/water mixture. The nickel(II) cations are bound in the complex through similar forces than the NH-proton in the ligand.