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.