Novel Metastable Structures of WO₃, MoO₃ and W_1‐<i>x</i>Mo_xO₃ Obtained by the Deintercalation of Layered Amine Adducts

Deintercalation of amines from the layered amine adducts of WO 3 , MoO 3 and W 1‐ x Mo x O 3 has been employed as a soft chemical route to produce unusual metastable structures of the oxides. After the adducts of WO 3 , MoO 3 and W 1– x Mo x O 3 ( x = 0.25, 0.5, 0.75) with amines such as triethylamine (TEA), pyridine, n ‐butylamine and n ‐octylamine had been characterized, deintercalation was carried out thermally as well as by acid leaching. Thermal deintercalation yielded novel metastable structures of WO 3 and MoO 3 that were significantly different from the stable forms, which contain distorted metal‐oxygen octahedra. Thus, ReO 3 ‐type cubic WO 3 was obtained by the thermal deintercalation of WO 3 · 0.5 TEA. Acid leaching of the amines gave metastable phases of WO 3 , MoO 3 and W 1‐ x Mo x O 3 , which were different from those obtained thermally. All the metastable phases transformed to the corresponding stable forms at higher temperatures.