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Research article2002Peer reviewed

Alkoxide Route to Mixed Oxides of Rhenium, Niobium, and Tantalum. Preparation and X-ray Single-Crystal Study of a Novel Rhenium-Niobium Methoxo Complex, Nb2(OMe)8(ReO4)2

Shcheglov, Pavel A.; Drobot, Dmitry V.; Seisenbaeva, Gulaim; Gohil, Suresh; Kessler, Vadim

Abstract

Thermal decomposition of complex oxomethoxo compounds Nb4O2(OMe)(14)(ReO4)(2) (I) and Ta4O2(OMe)(14)(ReO4)(2) (II) has been investigated. The decomposition of (II) at temperatures exceeding 100 degreesC results in the formation of MeOMe, MeOCH2OMe, MeOH, and H2O vapor and is accompanied by sublimation at temperatures over 135 degreesC. Plausible mechanisms of the processes studied are discussed. A new bimetallic methoxo compound, Nb-2(OMe)(8)(ReO4)(2) (III), was synthesized by interaction between Re2O7 and Nb-2(OMe)(10) in toluene solution and its structure was determined by means of an X-ray single-crystal study. The structure can be considered as a product of substitution for terminal methoxo groups with two perrhenate groups in dimeric Nb-2(OMe)(10) molecules. Decomposition of 11 in an inert atmosphere at 900 degreesC gave a Re-Ta mixed oxide phase, supposedly based on the L-Ta2O5 structure. Decomposition of I and III under similar conditions leads to the formation of rhenium-niobium oxide phases. The results obtained provide a basis for the alkoxide approach to the synthesis of oxide and metallic rhenium-based materials.

Published in

Chemistry of Materials
2002, Volume: 14, number: 5, pages: 2378-2383
Publisher: AMER CHEMICAL SOC