Reversible solid-state reaction between 18-Crown[6] and M[H2PO4] (M = K, Rb, Cs) and an investigation of the decomplexation process

Abstract

On heating the hydrated complexes 18-Crown[6]·M[H₂PO₄]·xH₂O (x = 2 for M = K, Rb; x = 1.5 for M = Cs), quantitatively prepared by mechanical mixing of crystalline 18-Crown[6] and M[H₂PO₄], to ca. 60 °C, water loss takes place, accompanied by the extrusion of the crown ether from the crystalline complex and followed by reconstruction of the inorganic phase M[H₂PO₄] (M = K, Rb, Cs); the resulting solid mixture reverts to 18-Crown[6]·M[H₂PO₄]·xH₂O (x = 2 for M = K, Rb; x = 1.5 for M = Cs) upon grinding in air.