[en] We study within an ionic model the structure and the energetics of neutral and charged clusters which may exist as structural units in molten ThCl₄ and in its liquid mixtures with alkali chlorides, with reference to Raman scattering experiments by Photiadis and Papatheodorou. As stressed by these authors, the most striking facts for ThCl₄ in comparison with other tetrachlorides (and in particular with ZrCl₄) are the appreciable ionic conductivity of the pure melt and the continuous structural changes which occur in the melt mixtures with varying composition. After adjusting our model to data on the isolated ThCl₄ tetrahedral molecule, we evaluate (i) the Th₂Cl₈ dimer and the singly charged species obtained by chlorine-ion transfer between two such neutral dimers; (ii) the ThCl₆ and ThCl₇ clusters both as charged anions and as alkali -compensated species; and (iii) various oligomers carrying positive or negative double charges. Our study shows that the characteristic structural properties of the ThCl₄ compound and of the alkali-Th chloride systems are the consequence of the relatively high ionic character of the binding, which is already evident in the isolated ThCl₄ molecular monomer. (author)