Interaction of 18-crown-6 with yttrium chloride: inner-sphere transformations of complexes under conditions of solid-state thermolysis

The reactions of YCl₂(H₂O)₆]Cl with 18-crown-6 in aliphatic alcohol solutions afford the complexes Y(H₂O)₃(18-crown-6)]Cl₃·1.25H₂O (1) and Y(H₂O)₈]Cl₃·(18-crown-6)·4H₂O (2), in which the inner coordination sphere of yttrium consists of nine and eight oxygen atoms, respectively. The inner-sphere transformations of complexes 1 and 2 under conditions of solid-state thermolysis were investigated. After the removal of coordinated water molecules from compound 1, the complex undergoes a structural transformation at temperatures above 180 °C, resulting in that two chloride anions enter into the coordination sphere of yttrium. For compound 2, a double exothermic effect is observed in the temperature range of 160–300 °C due to the formation of a certain new structural species containing chloride ions and 18-crown-6 in the inner coordination sphere.