Solid and gaseous thorium chloride compounds

VIIL2 Chlorine compounds and complexes VIII.2.1 Solid and gaseous thorium chloride compounds VIIL2.1.1 ThChCcr), ThChCcr) 

The experimental results on the existence of the lower thorium chlorides, ThCl2(cr) and ThClsCcr) are quite contradictory. 

Hayek et al. [1951HAY/REH] obtained products with compositions close to ThCl2 and ThCh from the reaction of thorium metal with gaseous chlorine in stoichiometric quantities while Jantsch and Homayr [1954JAN/HOM] reported the formation of ThCls as a result of the reduction of ThCh with aluminium and also, which is more surprising, from the thermal decomposition of ThCh at 673 K. As noted by Rand [1975RAN], contamination by oxygen and silica may have been serious in these experiments. 

Rand [1975RAN] notes that Dock [1965DOC] reported the formation of phases of composition close to ThCU and ThCls, with complicated X-ray patterns, as a result of the annealing of thorium metal-ThCl4 mixtures at 923-1073 K in tantalum containers. However, these results were subsequently described by the same group [1973CHI/FUL] as anomalous and probably caused by inadvertent contamination by oxygen or moisture. 

However, all of the emf results by Chiotti and Dock [1975CH1/DOC], Yoshida et al. [1967YOS/OYA], and Srinivasan and Flengas [1964SR1/FLE] failed to identify lower oxidation states of thorium in the Th-ThCLt system. The voltametric determina-tiorrs by Martinot [1986MAR4] also showed no evidence of the existence of Th(ll) in the eutectic system, even as an intermediate species. 

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