The nature of bonding in hexahalothorates and hexahalouranates(IV)

Abstract

Enthalpies of reaction have been determined by solution calorimetry for the process 2AX(c) + ThX4(c) = A2ThX6(c) where A = K, Cs and X = Cl, Br. The measurements afforded the following values of standard enthalpies of formation [Formula: see text], in kJ mol−1: K2ThCl6, −2108; Cs2ThCl6, −2151; K2ThBr,−1774; Cs2ThBr6,−1826. The standard enthalpies of formation of ThCl62− (g), ThBr62− (g), UCl62− (g), and UBr62− (g) and the two-halide ion affinities of ThCl4, ThBr4, UCl4, and UBr4 were compared by assuming semi-empirical (Kapustinskii) values of the lattice energies of the complexes. Homolytic and heterolytic bond energies were also calculated.