Intercalation of Cyclic Ethers into Vanadyl Phosphate VÌte œzslav Zima,* [a] Kla ¬ra Mela ¬nova ¬, [a] LudvÌk Benes œ, [a] Pavla C œ apkova ¬, [b] Miroslava Trchova ¬, [b] and Pavel Mate œjka [c] Abstract: Two cyclic ethers, tetrahydrofuran (THF) and tetrahydropyran (THP), were intercalated into vanadyl phosphate and characterized by X-ray powder diffraction, thermogravimetry, and IR and Raman spectroscopy. Both compounds contain one molecule of ether per formula unit of VOPO 4 and show high thermal stability in comparison with VOPO 4 intercalates with other organic guest molecules. Both ethers are anchored to the VOPO 4 host layers by their oxygen atoms, which are coordinated to the vanadium atoms of the host. The probable arrangement of the tetrahydropyran molecules in the host interlayer space is derived from molecular simulations by the Cerius 2 4.5 program. Keywords: intercalations ¥ molecular modeling ¥ vanadium ¥ vibrational spectroscopy ¥ X-ray diffraction Introduction Vanadyl phosphate dihydrate VOPO 4 ¥ 2H 2 O and other iso- structural layered compounds are able to accommodate some types of organic molecules in the interlayer space. [1] Aliphatic alcohols [2±5] and diols, [2, 6] amines, [7, 8] carboxylic acids, [9] car- boxamides, [10] amino acids, [11] ketones, [12] and aldehydes [13] are amongst the compounds, which can be intercalated in such a way. A great deal of attention was devoted to the intercalation of heterocyclic N and S donors. Pyridine and its derivatives, [14] imidazole, [15] pyrazole, pyrazine, and phenazine, [16] pyrrole and their derivatives, [17, 18] 2,2'-dithiodipyridine, [19] and tetra- thiofulvalene [20] were also intercalated into vanadyl phos- phate. On the other hand, intercalation of heterocycles with O donors into vanadyl phosphate has not been described yet. Intercalations of some crown ethers into montmorillonite [21, 22] and vanadium oxide xerogel [23] were studied. In these materials, some of the water molecules in their inter- layer space are replaced by crown ethers. Recently, poly- (ethylene glycol)s were intercalated into vanadyl phosphate and isostructural niobyl phosphate and arsenate. [24] It is presumed that the chains of the guests are deposited parallel to the host layer with every other oxygen atom of the guest coordinated to the vanadium or niobium atoms of the host layer. The chains are arranged in a bimolecular way in the interlayer space. Two types of VOPO 4 intercalates were formed depending on the temperature of the reaction. The high-temperature phase contains half the amount of the guest, and the guest chains are arranged in a monomolecular way. The present paper reports the results of the intercalation of tetrahydrofuran (THF) and tetrahydropyran (THP) into vanadyl phosphate. Results and Discussion Both guests cannot be intercalated directly in anhydrous vanadyl phosphate, and replacement of water molecules in VOPO 4 ¥ 2H 2 O does not lead to an intercalation. The intercalates had to be prepared by replacing 1-propanol or 2-propanol in the corresponding VOPO 4 intercalate with the desired guest. The intercalates prepared were yellow crystal- line solids, and this indicates that the vanadium( v) had not been significantly reduced. As confirmed by the results of elemental analyses, both intercalates contain one molecule of guest per formula unit. The diffractograms of both intercalates show a series of sharp (00l) reflections (Figure 1). The diffractogram of the THF intercalate contains a number of (hkl) diffraction lines that provide evidence of a regular structure. The lattice [a] Dr. V. Zima, Dr. K. Mela ¬nova ¬, Dr. L. Benes œ Joint Laboratory of Solid State Chemistry University of Pardubice, Studentska ¬ 84 53210 Pardubice (Czech Republic) Fax: ( 420)40-603-6011 E-mail: vitezslav.zima@upce.cz [b] Dr. P. C œ apkova ¬, Dr. M. Trchova ¬ Faculty of Mathematics and Physics Charles University, VHoles œovic œka ¬ch2 18000 Praha (Czech Republic) [c] Dr. P. Mate œjka Department of Analytical Chemistry Institute of Chemical Technology, Technicka ¬5 16628 Praha (Czech Republic) FULL PAPER Chem. Eur. J. 2002, 8, No. 7 ¹ WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 0947-6539/02/0807-1703 $ 20.00+.50/0 1703