Bimetallic alkoxides of niobium
TL;DR: In this article, the formation of the I-III group metal alkoxoniobates has been studied using the physicochemical analysis method, namely the investigation of solubility isotherms for the M 2 O 2 four-membered cycles in edge sharing octahedra.
About: This article is published in Polyhedron.The article was published on 1995-06-01. It has received 60 citations till now. The article focuses on the topics: Octahedron.
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TL;DR: In this article, the structural properties and applications of hetero(bi-and tri-)metallic alkoxides with halides and cyclopentadienyl ligands are discussed.
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TL;DR: In this article, the authors investigated the stability of the heterometallic complexes derived from the reactions of divalent metal acetylacetonates with metal isopropoxides.
Abstract: Interaction of Co(acac)2 with 2 eq. of Ti(OiPr)4 in hexane leads to an equimolar mixture of the new heterometallic complex [Co2Ti2(acac)2(OiPr)10] (1) and the known heteroleptic alkoxide Ti2(acac)2(OiPr)6. When redissolved in iPrOH 1 is destroyed, forming [Co2(acac)4(iPrOH)2] (2) as the only isolable crystalline product. Reaction of Co(acac)2 with 3 eq. of Ta(OiPr)5 gives [Co2Ta2(OiPr)14] (3) together with Ta(acac)(OiPr)4. Reaction of Ni(acac)2 with 4 eq. of Nb(OiPr)5 produces the heterometallic complex [NiNb2(OiPr)12] (4). Reactions of M(acac)2 (M = Co, Ni, Mg and Zn) with Al(OiPr)3 in 1 ∶ 2 ratios provides access to [MAl2(OiPr)4(acac)4] [M = Co (5), Ni (6), Mg (7)] and [Zn2Al2(OiPr)6(acac)4] (8) respectively. When redissolved in iPrOH, [NiAl2(OiPr)4(acac)4] (6) is destroyed, forming a mixture of [Ni2(acac)4(iPrOH)2] (9), Al(OiPr)3 and Al(acac)3. Interaction of M(acac)2, (M = Co, Ni) with metal isopropoxides in iPrOH as well as their recrystallization from iPrOH give 2 and 9 respectively. 5–7 are unstable in the hydrocarbon solution on heating, decomposing with formation of [M2Al2(OiPr)6(acac)4], along with Al(acac)3 and heterometallic alkoxide species. Mg(acac)2 was found to recrystallize unchanged from the solutions of Ti(OiPr)4 in toluene. The solution structure and stability of the heterometallic complexes has been investigated by UV-Vis spectroscopy and NMR, and the details of their decomposition on sublimation by mass-spectroscopy. The factors influencing the formation and stability of heterometallic complexes originating from the reactions of divalent metal acetylacetonates with metal isopropoxides are discussed.
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TL;DR: In this paper, a review of the pathways of formation of crystalline oligomeric oxoalkoxides is presented, which are products of partially controlled (or uncontrolled) hydrolysis, oxidation, thermal decomposition of mono-and bimetallic alkoxides of the ortho series.
Abstract: The review surveys the pathways of formation of crystalline oligomeric oxoalkoxides M
mO
n(OR)
p, which are products of partially controlled (or uncontrolled) hydrolysis, oxidation, thermal decomposition of mono- and bimetallic alkoxides of the ortho series M(OR)
n and M
mM
'n(OR)
p or elimination of ethers from these compounds. The physicochemical properties of oxoalkoxides (solubility, the behaviour in solutions, volatility,
etc.) differ considerably from the properties of the corresponding alkoxides. Hence, oxoalkoxides can be considered as immediate precursors of oxide materials produced by sol–gel technology. The M
mO
n(OR)
p compounds are classified according to the sizes of associates. The crystal chemistry of alkoxides is discussed. The bibliography includes 249 references.
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TL;DR: In this article, a characterization of Zr{sub 2}(O{sup i}Pr), sub 8}(sup i)PrOH, sub 2} by {sup 1}H and {sup 13}C NMR spectroscopy, ir spectroscopic, and single-crystal x-ray diffraction is reported.
Abstract: Characterization of Zr{sub 2}(O{sup i}Pr){sub 8}({sup i}PrOH){sub 2} by {sup 1}H and {sup 13}C NMR spectroscopy, ir spectroscopy, and single-crystal x-ray diffraction ({minus}100{degree}C) is reported. The unit cell contains four half-dimers in the asymmetric unit, all of which differ only in the rotational conformation about Zr-O and O-C bonds. In each dimer, the edge-shared bioctahedron has two {mu}-O{sup i}Pr groups. On opposite sides of this Zr{sub 2}({mu}-OR){sub 2} plane, each dimer forms two hydrogen bonds, one each between a coordinated alcohol and a terminal alkoxide. The NMR spectra at 25{degree}C are so simple as to be structurally uninformative, a result of rapid fluxionality which includes, as one component, proton migration among all O{sup i}Pr units. At {minus}80{degree}C in toluene, the NMR spectra are now too complex to be accounted for by a single edge-shared bioctahedral structure. The hafnium analogue is isomorphous with the zirconium compound. Although Ce{sub 2}(O{sup i}Pr){sub 8}({sup i}PrOH){sub 2} is not isomorphous, it exhibits an analogous hydrogen-bonded structure in which the O{hor ellipsis}O distance is as short as it is in the Zr analogue, in spite of a metal-metal separation which is longer by 0.28 {angstrom}. The generality of hydrogen bonding between M-OR and M-O(H)R groups whenmore » they are aligned parallel in a metal cluster is reviewed. 44 refs., 2 figs., 4 tabs.« less
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TL;DR: The 1H NMR spectra for each compound was consistent with the X-ray crystal structure and variable-temperature studies showed fluxionality in the indium complex as discussed by the authors.
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TL;DR: In this paper, a complete crystallographic study of these crystals was carried out, and the results were presented in the form of a 2-5 mm in length and a transparent crystal.
Abstract: In the investigation of the sol-gel processing, it has been noted that this process provides a means of producing high-purity homogeneous material of the desired stoichiometric composition such as metal alkoxide complexes. Lithium niobate ceramics were produced by reaction of equimolar quantities of lithium ethoxide and niobium ethoxide. Evaporation of the ethanolic solution at room temperature produced crystals that were transparent and 2-5 mm in length. A complete crystallographic study of these crystals was carried out, and the results are presented herein. 12 refs., 2 figs.
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