Complex Thorium Chlorides

Thorium chloride forms compounds with 4, 6, 7, 12, and 18 molecules of ammonia, of which ThCl₄.4NH₃ is the only compound stable above 120° C.; when heated it forms successively Th(NH₂)₄ and Th(NH₂)₂. Thorium chloride also forms addition compounds with various organic bases, and with ethyl alcohol, acetone, and various aldehydes.

Thorium chloride shows some tendency to combine with alkali or other chlorides to form complex salts, which, however, are not very well defined. Berzelius appears to have obtained a potassium thorium fluoride, to which Cleve attributed the formula 2ThCl₄.KCl.18H₂O; whilst Chydenius obtained the salt ThCl₄.8NH₄Cl.8H₂O. Wells and Willis prepared the caesium salts 3CsCl.ThCl₄.12H₂O and 2CsCl.ThCl₄.11H₂O; but on account of the hygroscopic nature of these compounds there was some uncertainty as to the amount of their water of crystallisation. Chauvenet has prepared a number of double chlorides of thorium and the alkali metals, with and without water of crvstallisation. Cleve obtained the platinum compound ThCl₄.PtCl₄.12H₂O, and Nilson the compound 2ThCl₄.3PtCl₂.24H₂O; the pyridine and quinoline salts (C₅H₅N)₂.H₂ThCl₆ and (C₉H₇N)₂.H₂ThCl₆ respectively, have also been obtained.