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Alkoxide complexes of rhenium, niobium and tantalum

Nikonova, Olesya A. (2009). Alkoxide complexes of rhenium, niobium and tantalum. Uppsala : Sveriges lantbruksuniv.
ISBN 978-91-86197-17-9
[Licentiate thesis]

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Abstract

This thesis describes two major methods for preparation of new mono-, bi- and trimetallic complexes on the basis of Rhenium, Niobium and Tantalum: (1) - the electrochemical method for the synthesis of Re4O4(OEt)12 and (2) - the interaction of Rhenium heptoxide, Re2O7, with alkoxo-derivates of Niobium and/or Tantalum, M2(OR)10 for the synthesis of bi- and trimetallic complexes of common formula (M1-xM'x)4O2(OR)14(ReO4)2 (M = Nb; M' = Ta; R = Me, Et), where x = 0–1. The structures of these complexes were determined by single-crystal X-ray diffraction. The products were also characterized by IR, NMR and X-ray powder diffraction. The influence of the increasing ligand size on the solubility and stability of the complexes Re4O4(OEt)12 and M4O2(OR)14(ReO4)2 (M = Nb, Ta; R = Me, Et) has been established. The effect of the ligand and metal ion ratio on the conditions and the chemical composition of the products of thermal treatment have been investigated. Nanosized Rhenium metal particles (approximately 3 nm in diameter) were obtained from Re4O4(OEt)12 by thermal decomposition in inert atmosphere at as low temperature as 380 °C. Semi-ordered macro porous monoliths with the pore size in the range 100 – 250 nm, with the crystal structure related to the block structures of the L-modification of Ta2O5, were produced from trimetallic complexes of the common formula (Nb1-xTax)4O2(OMe)14(ReO4)2 (x = 0.3, 0.5, 0.7) via thermal decomposition in air at the temperatures ≤ 1000 °C. The thermal decomposition in dry nitrogen atmosphere provides formation of solid solutions, which possess the structures related to the block structure of the H-modification of Nb2O5 for the Niobium-rich precursors and block structure of the L-modification of Ta2O5 for Ta:Nb ≤ 1:1 at the temperatures ≤ 1000 °C.

Authors/Creators:Nikonova, Olesya A.
Title:Alkoxide complexes of rhenium, niobium and tantalum
Year of publishing :2009
Number of Pages:53
Papers/manuscripts:
NumberReferences
ALLI Nikonova O.A., Jansson K., Kessler V. G., Sundberg M., Baranov A.I., Shevelkov A.V., Drobot D.V., Seisenbaeva G. A. (2008). Electrochemical Synthesis, Structural Characterization and Decomposition of Rhenium Oxoethoxide, Re4O4(OEt)12. Ligand Influence on the Structure and Bonding in the High-Valent Tetranuclear Planar Rhenium Alkoxide Clusters. Inorganic Chemistry 47, 1295-1300. II Nikonova O.A., Kessler V.G., Seisenbaeva G.A., Drobot D.V., Shcheglov P.A. (2007). Synthesis and X-ray Single Crystal Study of Niobium and Tantalum Oxo-Ethoxo-Perrhenates M4O2(OEt)14(ReO4)2. Polyhedron 26(4), 862-866. III Nikonova O.A., Seisenbaeva G.A., Kessler V.G., Shcheglov P.A., Drobot D.V. (2007). Comparative Study of Bimetal Alkoxo Complexes of Rhenium, Niobium and Tantalum by Single-Crystal X-ray Diffraction and IR Spectroscopy. Russian Journal of Inorganic Chemistry 52(11), 1687-1692. IV Nikonova O.A., Kessler V.G., Seisenbaeva G.A.(2008). Substitution Features in the Isomorphous Replacement Series for Metal-Organic Compounds (NbxTa1-x)4O2(OMe)14(ReO4)2, x = 0.7, 0.5, 0.3—Single-Source Precursors of Complex Oxides with Organized Porosity. Journal of Solid State Chemistry 181(12), 3294-3302.
Place of Publication:Uppsala
ISBN for printed version:978-91-86197-17-9
Language:English
Publication Type:Licentiate thesis
Full Text Status:Public
Agrovoc terms:chemical synthesis, complexing, x rays
Keywords:alkoxide, Rhenium, Niobium, Tantalum, nanomaterials, semi-ordered macro porous materials, single-crystal X-ray diffraction, SEM.
URN:NBN:urn:nbn:se:slu:epsilon-2870
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-2870
ID Code:2004
Department:(NL, NJ) > Dept. of Chemistry (until 131231)
Deposited By: Olesya Nikonova
Deposited On:13 May 2009 00:00
Metadata Last Modified:02 Dec 2014 10:15

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