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1.
Matthias Bauer Christoph Gastl Christoph K?ppl Guido Kickelbick Helmut Bertagnolli 《Monatshefte für Chemie / Chemical Monthly》2006,383(1):567-581
The molecular structure of the transition metal alkoxide Zr(OnBu)4 in toluene and its modification by addition of i-propanol, tetrahydrofurane, and the coordinating ligand pentane-1,3-dione (Hacac) were investigated by extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopy.
Zr(OnBu)4 dissolved in toluene forms dimers. It was proved that cluster size is a function of the number of added equivalents ligand.
In contrast, the addition of i-propanol or tetrahydrofurane caused no structural changes observable by EXAFS spectroscopy. A detailed discussion of the
structural models is given in terms of possible alternatives and errors within the EXAFS analysis. 相似文献
2.
Gerald I. Spijksma Gulaim A. Seisenbaeva Andreas Fischer Henny J. M. Bouwmeester Dave H. A. Blank Vadim G. Kessler 《Journal of Sol-Gel Science and Technology》2009,51(1):10-22
Long-term storage at 0 °C of a paraffin-sealed flask with commercial 70 wt% solution of zirconium n-propoxide in n-propanol resulted in crystallization of an individual oxoalkoxide complex Zr4O(OnPr)14(nPrOH)2 in over 20% yield. The structure of this molecule can be described as a triangular Zr3(μ3-O)(OR)10(ROH) core of 3 edge-sharing octahedrons with an additional Zr(OR)4(ROH) unit attached through a pair of (μ-OR) bridges. Mass spectrometric and 1H NMR investigation of the commercial samples of the most broadly applied zirconium and hafnium n-propoxides and n-butoxides indicate the presence of analogous species in the commercial alkoxide precursors. The content of oxo-alkoxide species
in the commercial precursors has been estimated to be ~20% for n-propoxide and ~35% for zirconium n-butoxide. A new route has been presented for synthesis of the individual crystalline mixed ligand precursor [Zr(OnPr)(OiPr)3(iPrOH)]2, from zirconium n-propoxide. A high yield has been observed (~90%), indicative of an almost complete precursor transformation. Mass spectrometry
has shown that the synthesized mixed ligand precursor is dimeric, which makes it an attractive alternative to zirconium n-propoxide. Addition of 1 eq of Acetylacetone to zirconium or hafnium alkoxide precursors results in formation of dimeric
[M(OR)3(acac)]2 in high yields. These species have limited stability (much higher for Hf than for Zr) and transform in solution into hydrolysis-insensitive
M(acac)4 through very unstable M(acac)3(OR) intermediates containing 7-coordinated metal centers. This transformation can be followed kinetically in hydrocarbon
solvents by 1H NMR and is noticeably accelerated by addition of parent alcohols. The obtained results clearly reveal limited applicability
of EXAFS and XANES techniques for the study of such systems, especially in the context of structure prediction.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
3.
Summary. The molecular precursors Nb(OiPr)2[OSi(OtBu)3]3 and {Nb(OiPr)4[O2P(OtBu)2]}2 have been prepared. The first compound undergoes facile thermal conversion to high surface area, acidic niobia silica, whereas
the second one thermally decomposes to a low surface area niobium phosphate. 相似文献
4.
Summary. The methacrylate-substituted clusters Hf4O2(OMc)12, Hf6O4(OH)4(OMc)12(BuOH), Ti4Hf4O6(OBu)4(OMc)16, and Ti2Zr5HfO6(OMc)20 (OMc=methacrylate) were prepared by reacting Hf(OBu)4, or Hf(OBu)4/Ti(OBu)4 and Hf(OBu)4/Zr(OBu)4/Ti(OBu)4 mixtures, respectively, with methacrylic acid. All clusters were characterized by X-ray structure analyses and are basically isostructural, although not in each case isomorphous, with the corresponding oxozirconium clusters. Low-temperature NMR studies revealed that the methacrylate ligands of Hf4O2(OMc)12 are highly dynamic even at –80°C.Received February 17, 2003; accepted February 21, 2003
Published online June 2, 2003 相似文献
5.
V. V. Burlakov V. S. Bogdanov K. A. Lyssenko A. Spannenberg P. V. Petrovskii W. Baumann P. Arndt M. Kh. Minacheva B. N. Strunin U. Rosenthal V. B. Shur 《Russian Chemical Bulletin》2012,61(1):165-173
The interaction of the Negishi reagent Cp2ZrBun 2 with 1,4-bis(tert-butyl)butadiyne ButC≡C-C≡CBut leads to four products: a five-membered zirconacyclocumulene complex Cp2Zr(η4-ButC4But) (2) synthesized earlier by another method, the previously unknown seven-membered zirconacyclocumulene Cp2Zr[η4-ButC4(But)-C(C2But)=CBut] (3) as well as small amounts of the zirconocene binuclear butatrienyl complex Cp2(Bun)Zr(ButC4But)Zr(Bun)Cp2 (4), and the dimeric acetylide [Cp2ZrC≡CBut]2 (5). The structure of complexes 2–5 was established by X-ray diffraction studies. 相似文献
6.
New tri-functional ligands of the type R2NCOCH2SCH2CONR2 (where R = iso-propyl, n-butyl or iso-butyl) were prepared and characterized. The coordination chemistry of these ligands with uranyl and lanthanum(III) nitrates was studied by using the IR, 1HNMR and elemental analysis methods. Structures for the compounds [UO2(NO3)2(iPr2NCOCH2SCH2CONiPr2)] [UO2(NO3)2(iBu2NCOCH2SCH2CONiBu2)], [La(NO3)3(iPr2NCOCH2SCH2CONiPr2)2] and [La(NO3)3(iBu2NCOCH2SCH2CONiBu2)2] were determined by single crystal X-ray diffraction. These structures show that the ligand acts as a bidentate chelating ligand and bonds through both the carbamoyl groups to the uranyl and lanthanum(III) nitrate groups. Solvent extraction studies show that the ligand can extract the uranyl ion from the nitric acid medium but does not show any ability to extract the americium (III) ion. 相似文献
7.
《Journal of Coordination Chemistry》2012,65(20):3620-3626
A new tri-functional ligand iBu2NCOCH2SOCH2CONiBu2 was prepared and characterized. The coordination chemistry of this ligand with uranyl nitrate was studied with IR, 1H NMR, electrospray mass–spectrometry, thermogravimetry, and elemental analysis. The structure of [UO2(NO3)2(iBu2NCOCH2SOCH2CONiBu2)] was determined by single-crystal X-ray diffraction. The uranium(VI) ion is surrounded by eight oxygens in a hexagonal bipyramidal geometry. Four oxygens from two nitrates and two oxygens from the ligand form a planar hexagon. The ligand is a bidentate chelate, bonding through sulfoxo and one of the carbamoyl groups to uranyl nitrate. 相似文献
8.
Gunnar Westin Marat Moustiakimov Mikael Kritikos 《Journal of Sol-Gel Science and Technology》2003,26(1-3):115-118
A new chloro-oxo-alkoxide, Sr2Er2OCl(OPr
i
)7(HOPr
i
)4 has been prepared by reacting 4ErCl3 with 5Sr dissolved in toluene:HOPr
i
. The structure, determined by single-crystal X-ray techniques, is built from two polymer strands, each formed by repeating two molecular Sr2Er2O(OPr
i
)7(HOPr
i
)4 complexes, inter-tied by a chloro atom. The four independent, but very similar complexes contain two Er and two Sr ions, all binding to a central oxo ion. The great similarity of the FT-IR and UV-vis-NIR spectra of the solid and the hexane/toluene/2-propanol solutions shows that the molecular complexes have similar complex structures in the solid state and in solution. 相似文献
9.
V. V. Popov V. F. Petrunin S. A. Korovin A. P. Menushenkov O. V. Kashurnikova R. V. Chernikov A. A. Yaroslavtsev Ya. V. Zubavichus 《Russian Journal of Inorganic Chemistry》2011,56(10):1538-1544
The formation of (Ln3+)2(M4+)2O7 (Ln = Gd, Dy; M = Zr, Hf) nanocrystallites obtained by annealing mixed hydroxides LnM(OH)7 · nH2O (precursors) synthesized by coprecipitation has been studied by synchronous thermal analysis, X-ray diffraction (normal
and anomalous diffraction of synchrotron radiation), and EXAFS. In the systems under consideration, heat treatment of the
X-ray amorphous precursors leads to their dehydration, and at 600–700°C, nanocrystallites with an fcc structure of disordered
fluorite start forming. A further increase in temperature is accompanied by crystallite growth (CDD) and considerable change
in the local structure of the heat-treated compounds. The crystallization enthalpies and activation energies have been determined. 相似文献
10.
Guido Kickelbick Martin P. Feth Helmut Bertagnolli Bogdan Moraru Gregor Trimmel Ulrich Schubert 《Monatshefte für Chemie / Chemical Monthly》2002,133(6):919-929
Summary. The surface-modified oxometallate clusters Zr6(OH)4O4(OMc)12, Ti4Zr4O6(OBu)4 (OMc)16, and Ti2Zr4O4(OBu)2(OMc)14 (OMc = methacrylate) as well as their nanocomposites with polystyrene, poly(methacrylic acid) and poly(methyl methacrylate) were
investigated by EXAFS. Studies on the nanocomposites revealed that the structure of the cluster core is retained in the hybrid
materials.
Received October 23, 2001. Accepted November 12, 2001 相似文献
11.
Eric C. Moinet Dr. Benjamin M. Wolf Dr. Olivier Tardif Dr. Cäcilia Maichle-Mössmer Prof. Dr. Reiner Anwander 《Angewandte Chemie (International ed. in English)》2023,62(17):e202219316
Lanthanide (Ln) tetraisobutylaluminates constitute key components in commercial 1,3-diene polymerization catalysts, and likewise are the homogeneous rare-earth-metal catalysts of prime industrial importance. Discrete divalent rare-earth-metal complexes [Ln(AliBu4)2] (Ln=Sm, Eu, Yb) reported here display the first structurally characterized homoleptic metal tetraisobutylaluminates. Treatment of [Ln(AliBu4)2] with C2Cl6 gives access to SmII/SmIII mixed-valence cluster [Sm6Cl8(AliBu4)6] and the YbII cluster [Yb4Cl4(AliBu4)4], respectively. Reaction with B(C6F5)3 leads to hydride abstraction and formation of arene-coordinated hydroborates such as [Sm{HB(C6F5)3}2(toluene)2]. Complexes [Ln(AliBu4)2] engage in single-component isoprene polymerization, affording high cis-1,4 polyisoprenes with narrow molecular weight distributions. Binary [Yb(AliBu4)2]/[HNPhMe2][B(C6F5)4] fabricates polyisoprene in a perfectly living manner. The catalytically active species are scrutinized by NMR spectroscopy. 相似文献
12.
The molecular precursors Nb(OiPr)2[OSi(OtBu)3]3 and {Nb(OiPr)4[O2P(OtBu)2]}2 have been prepared. The first compound undergoes facile thermal conversion to high surface area, acidic niobia silica, whereas
the second one thermally decomposes to a low surface area niobium phosphate. 相似文献
13.
Silvia Gross Guido Kickelbick Michael Puchberger Ulrich Schubert 《Monatshefte für Chemie / Chemical Monthly》2003,48(9):1053-1063
The methacrylate-substituted clusters Hf4O2(OMc)12, Hf6O4(OH)4(OMc)12(BuOH), Ti4Hf4O6(OBu)4(OMc)16, and Ti2Zr5HfO6(OMc)20 (OMc=methacrylate) were prepared by reacting Hf(OBu)4, or Hf(OBu)4/Ti(OBu)4 and Hf(OBu)4/Zr(OBu)4/Ti(OBu)4 mixtures, respectively, with methacrylic acid. All clusters were characterized by X-ray structure analyses and are basically isostructural, although not in each case isomorphous, with the corresponding oxozirconium clusters. Low-temperature NMR studies revealed that the methacrylate ligands of Hf4O2(OMc)12 are highly dynamic even at –80°C. 相似文献
14.
Zhdanov A. P. Lisovsky M. V. Goeva L. V. Razgonyaeva G. A. Polyakova I. N. Zhizhin K. Yu. Kuznetsov N. T. 《Russian Chemical Bulletin》2009,58(8):1694-1700
The reactions of salts of the anion [2-B10H9(N≡CMe)]− with aliphatic alcohols ROH (R = C
n
H2n+1 (n = 1–6) CH2CH2(OEt), Pri, Bui, But, i-C5H11) are studied. These reactions result in hydrolytically stable imidates [2-B10H9{NH=C(OR)Me}]−. Their structures were confirmed by the data from mass spectrometry, IR, 1H, 11B, and 13C NMR spectroscopy. The molecular geometry of [2(Z)-B10H9{NH=C(OBu)Me}]−, which formed in nucleophilic addition reaction of n-butyl alcohol to [2-B10H9(N≡CMe)]−, was established by X-ray diffraction analysis. 相似文献
15.
E. P. Turevskaya N. I. Kozlova N. Ya. Turova A. L. Belokon' D. V. Berdyev V. G. Kessler Yu. K. Grishin 《Russian Chemical Bulletin》1995,44(4):734-742
The direct electrochemical synthesis of zirconium (1a) and hafnium (1b) alkoxides, M(OPri)4·PriOH, Zr(OBui)4·BuiOH (4a) and M(OR)4, where R=Et (2a,b), Bun (3a), Bus (5a), C2H4OMe (6a,b) has been carried out by anodic oxidation of metals in anhydrous alcohols in the presence of LiCl as a conductive additive to give quantitative yields. The solubility polytherms and dissociation pressure of1a,b have been investigated. It has been proved by means of chemical analysis, X-ray powder, and IR spectral studies that the desolvation of 1a,b and Sn(OPri)4·PriOH (1c) is accompanied by the formation of amorphous oxocompounds M3O(OPri)10. On the basis of1H NMR data it has been proved that the structure of the latter is analogous to that of known triangular cluster molecules M3(3-O)(3-OR)(-OR)3(OR)6, where M=Mo, W, U. Mass-spectral data and the determined physicochemical characteristics of1–5 permit to conclude that the samples of composition M(OR)4, where M=Zr, Hf, and2,3,5 contain tri- and tetranuclear oxocomplexes M3O(OR)10 and M4O(OR)14 respectively, along with Zr(OR)4 oligomers of different molecular complexity.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 752–760, April, 1995. 相似文献
16.
From the reaction of [Nb6Cl14(H2O)4] · 4H2O with acetic anhydride in the presence of an excess of (nBu4N)F the novel cluster compounds (nBu4N)2[Nb6Cli4(OAc)i8Cla6] ( 1 ) and (nBu4N)2[Nb6(OAc)i12Cla6] ( 2 ) (OAc = acetato ligand) are obtained. They are the first examples of hexanuclear niobium cluster compounds with acetato ligands on the inner sites of the metal atom octahedron. The crucial role of the presence of fluoride ions in the synthesis is discussed. Each acetato ligand bridges in a μ2-η1-fashion with one O atom an edge of the metal atom octahedron. The monoclinic crystals of 1 consist of discrete (nBu4N)+ cations and [Nb6Cli4(OAc)i8Cla6]2– cluster anions. They are oxidized by two electrons with respect to the cluster starting material. Besides the syntheses of 1 and 2 , the structure of 1 and spectral properties of both compounds are reported. 相似文献
17.
Simon Trudel E. Daryl Crozier Peter S. Budnik 《Journal of solid state chemistry》2011,184(5):1025-19128
The oxidation state and local geometry of the metal centers in amorphous thin films of Fe2O3 (Fe3+ oxidation state), CoFe2O4 (Co2+/Fe3+ oxidation states), and Cr2O3 (Cr3+ oxidation state) are determined using K edge X-ray absorption near-edge structure (XANES) spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. The metal oxide thin films were prepared by the solid-state photochemical decomposition of the relevant metal 2-ethylhexanoates, spin cast as thin films. No peaks are observed in the X-ray diffraction patterns, indicating the metal oxides are X-ray amorphous. The oxidation state of the metals is determined from the edge position of the K absorption edges, and in the case of iron-containing samples, an analysis of the pre-edge peaks. In all cases, the EXAFS analysis indicates the first coordination shell consists of oxygen atoms in an octahedral geometry, with a second shell consisting of metals. No higher shells are observed beyond 3.5 Å for all samples, indicating the metal oxides are truly amorphous, consistent with X-ray diffraction results. 相似文献
18.
Mono- and bi-nuclear Zr(IV) β-ketodiester complexes of general formulas [Zr(dtbacdc)4] (1), [Zr(dmacdc)3(OiPr)]2 (2), and [Zr(dtbacdc)3(OiPr)]2 (3), (dtbacdc = di-tert-butyl-1,3-acetonedicarboxylato and dmacdc = dimethyl-1,3-acetonedicarboxylato ligands) were successfully isolated, when zirconium(IV)
isopropoxide reacted with the four- ((1)) or twofold ((2), (3)) excess of di-alkyl 1,3-acetonedicarboxylates (CO(CH2COOR′)2, R′ = Me, tBu). Analysis of single-crystal X-ray diffraction data showed that (1) crystallizes in the monoclinic system (C 2/c (no. 15)). The structure of this compound consists of monomers, which are composed of Zr(IV) ions surrounded by eight oxygen
atoms derived from four chelating β-ketodiester ligands. The stoichiometry and the bi-nuclear structure of (2) and (3) using spectroscopic methods (IR and NMR), and mass spectrometry have been determined. Thermal analysis and variable temperature
IR (VT-IR) spectroscopy have been used to study the thermal stability and thermal decomposition pathway of synthesized Zr(IV)
compounds. 相似文献
19.
Thermal properties of organoindium thiolates were investigated by means of thermogravimetric (TG) and differential thermal (DT) analysis. Dibutyl-indium propylthiolates (Bun2InSPrn, Bun2InSPri, Bui2InSPrn and Bui2InSPri) decomposed up to 280°C along with an exothermic DT peak and gave indium(I) sulfide (InS) powders. Although the arylthiolate Bun2InSPh also afforded InS powders, it decomposed at a slightly higher temperature. In contrast, the dithiolate and the dithiocarbamate complexes [BunIn(SPri)2 and In (S2CNBu2)3] gave indium(III) sulfide (In2S3) powders. 相似文献
20.
Abbas Tarassoli Ziba Khodamoradpur 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):527-532
Abstract The reaction of bis(anilino)phosphine oxide (C6H5NH)2P(O)H, 1 with Bu2 nSnCl2 in the presence of an excess of triethylamine (TEA) in dry tetrahydrofurane (THF) yields the novel N,O-bonded tin complex Bu2 nSn[NPh(O)P(H)NPh(HNEt3)]2, 2. TEA is used as a base to deprotonate the phosphazane ligand and is separated as Et3NH+Cl?, whereas HTEA+ exists in the final product 2 and act as a charge balancing and H-bond structure–directing agent. This new compound has been fully characterized by means of IR, MS, and multinuclear (1H, 31P, and 119Sn NMR) spectroscopy. 相似文献