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Synthesis, structure determination, and sol-gel processing of heterometallic heteroleptic alkoxide complexes of late transition metals

Werndrup, Pia (2005). Synthesis, structure determination, and sol-gel processing of heterometallic heteroleptic alkoxide complexes of late transition metals. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2005:27
ISBN 91-576-7026-9
[Doctoral thesis]



The thesis describes synthesis of single-source precursors (SSP) for sol-gel preparation of thin films and nanocomposites. The structures of the SSPs were determined by single-crystal X-ray studies and a new group of heterometallic heteroleptic alkoxide complexes have been described, the MII2MV2(acac)2(OR)12 complex, MII= Co, Ni, Zn or Mg, and MV= Ta or Nb, R= Et or Me. Changing to molybdenum oxomethoxide, MoO(OMe)4, instead of tantalum or niobium alkoxide, in the reaction with cobalt acetylacetone provided Co2Mo2O2(acac)2(OMe)10. Nickel acetylacetonate in the reaction with MoO(OMe)4 provided Ni2Mo2O2(acac)2(OMe)10. In order to improve solubility, the acetylacetonate complex was exchanged for Ni(ORN)2 (RN= CHMeCH2NMe2) and the reaction provided Ni2Mo2O2(ORN)2(OMe)10. The structure of Ni2Mo2O2(L)2(OMe)10, L= acac or ORN, was determined by EXAFS. Nanocomposite powder was produced by hydrolysis and condensation of the SSPs, with toluene as solvent. The xerogel powders from Ni2Mo2O2(ORN)2(OMe)10 were annealed at different temperatures and showed increasing degree of crystallization of the material. At 700 °C, crystallized grains could be seen, with low porosity but a large surface area provided by the grain size (175-250 nm). The oxide powders obtained at 650 °C and 800 °C from Co2Ta2(acac)2(OMe)12 showed dense and well-faceted xerogel particles with an even size distribution. Small islands of a crystallized oxide phase could be seen on the surface of the particles. Thin films were produced by spin-coating on Si and SiO2. SEM images of the oxide films from Co2Ta2(acac)2(OEt)12 revealed smooth and evenly distributed films on the substrates. The different layers were not seen, indicating uniform depositions. Zeolite Y (12 Å pores) was used for implementation of MII2MV2(acac)2(OMe)12. The implemented zeolite complex was studied by EXAFS and the catalysis ability was tested. For modelling experiments, synthesis between Co2Nb2(acac)2(OMe)12 and cyclohexylsilsesquioxane was performed and resulted in Co[(C6H11)7Si7O12]2H4. According to the very similar FT of the EXAFS analyses of the implemented zeolite and the Co-silsesquioxane complex, the metallasilsesquioxane complex can serve as a zeolite Y analogue with implemented metal atoms.

Authors/Creators:Werndrup, Pia
Title:Synthesis, structure determination, and sol-gel processing of heterometallic heteroleptic alkoxide complexes of late transition metals
Year of publishing :2005
Number of Pages:48
ALLI. P. Werndrup, S. Gohil, V. G. Kessler, M. Kritikos and L. G. Hubert-Pfalzgraf, Synthesis, characterization and molecular structures of homo- and heterometallic nickel(II) aminoalkoxides Ni(h2-ORN)2 and Ni(Ni0.25Cu0.75)2(µ3-OH)(µ-OAc)(h1-OAc)2(µ,h2-ORN)2(h2-RNOH) (RN=CHMeCH2NMe2). Polyhedron, 2001, 20, 2163-2169. II. P. Werndrup and V. G. Kessler, Interaction of Co(acac)2 and Ta(OMe)5: Isolation and X-ray Single Crystal Study of the Products. MII2MV2(acac)2(OMe)12, MII=Co, Ni, Zn, Mg and MV=Ta, Nb - A New Class of Heterometallic Heteroleptic Alkoxide Complexes. J. Chem. Soc., Dalton Trans., 2001, 574-579. Reproduced by permission of The Royal Society of Chemistry. III. P. Werndrup, G. A. Seisenbaeva, G. Westin, I. Persson and V. G. Kessler, Single-Source Precursor Approach to Late Transition Metal Molybdate Materials. The Structural Role of Chelating Ligands in the Formation of Heterometallic Heteroleptic Alkoxide Complexes. Inorg. Chem. Submitted for publication. Reproduced with permission from Inorganic Chemistry. Unpublished work copyright 2005 American Chemical Society. IV. P. Werndrup and V. G. Kessler, Application of MII2MV2(acac)2(OMe)12 Derivatives in Sol-Gel Preparation of Oxide and Oxide Nanocomposite Materials for Catalysis. J. Sol-Gel Sci. Tech., 2003, 26, 883-886. Published with kind permission of Springer Science and Business Media. V. P. Werndrup, M. Verdenelli, F. Chassagneux, S. Parola and V. G. Kessler, Powders and Dense Thin Films of Late Transition Metal Oxide Nanocomposites from Structurally Characterized Single-Source Precursors. J. Mater. Chem., 2004, 14, 344-350. Reproduced by permission of The Royal Society of Chemistry. VI. P. Werndrup and V. G. Kessler, Bis-silsesquioxane Complex as a Molecular Model of Transition Metal Oxide-Zeolite Nanocomposite. Inorg. Chem. Comm., 2004, 7, 588-591.
Place of Publication:Uppsala
ISBN for printed version:91-576-7026-9
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:X Agricola extesions > X50 Chemistry
Subjects:Not in use, please see Agris categories
Keywords:sol-gel, alkoxide, single-source precursors, nanocomposite materials, zeolite, silsesquioxanes, single-crystal X-ray, EXAFS, SEM.
Permanent URL:
ID Code:794
Department:(NL, NJ) > Dept. of Chemistry (until 131231)
Deposited By: Pia Werndrup
Deposited On:22 Mar 2005 00:00
Metadata Last Modified:02 Dec 2014 10:07

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