Intercalation of tris(2,2′-bipyridme)ruthenium(II) into a layered silicate, magadiite, with the aid of a crown ether

Intercalation of the tris(2,2′-bipyridine)ruthenium(II) complex cation into a layered silicate (magadiite; the ideal formula is Na₂Si₁₄O₂₉·nH₂O) was investigated. Since the complex cation did not intercalate by a direct ion exchange reaction with the interlayer sodium ions in an aqueous medium, a crown ether, 15-crown-5, was added in the reactant to promote the ion-exchange reaction. Two possible reaction mechanisms were proposed for the present ion-exchange reaction: One is a two-step reaction, where 15-crown-5 was first intercalated into the interlayer space of Na-magadiite and exchanged with tris(2,2′-bipyridine)ruthenium(II) complex cation subsequently. The other is a one-step reaction, where 15-crown-5 forms complex ions with sodium ions deintercalated from the interlayer space and the tris(2,2′-bipyridine)ruthenium(II) complex cation is intercalated into the interlayer space to compensate the charge balance. The present success opens up new opportunities to introduce organic cations into the interlayer space of various layered solids.