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1.
Homoleptic and mixed -zirconium phosphonates (ZrPs) -Zr(O 3PR) 2 (R = Me, Bu n, Bu i, Hex, Oct and Ph) and -Zr(O 3PR 1) 2−x(O 3PR 2) x were readily prepared in high yields from zirconyl choride and the corresponding phosphonic acids in suitable solvent mixtures under hydrothermal conditions at low fluoride concentrations. They form crystalline aggregates consisting of platelets from ca. 10–20 monolayers thickness, with well-defined surface structures. Impregnation with Cp 2ZrCl 2 by sublimation or slurry methods provided the first examples of ZrP-supported alkene polymerization catalysts. Crystal morphology and interlayer spacing are unaffected by the impregnation process. Solid-state NMR spectroscopy provides evidence for the integrity of the adsorbed metallocene structure. Covalent attachment of Cp *ZrCl 3 to functionalized ZrPs of the type -Zr(O 3PR 1) 1.8(O 3PC nH 2nOH) 0.2 is similarly possible. The new catalysts polymerize ethene with good to excellent activities under mild conditions, even at remarkably low methylalumoxane/zirconocene ratios of 10:1. The polymer is obtained as free-flowing particles, which reflect the morphology of the catalyst supports. 相似文献
2.
Structure, electronic state and energy of Si nC − and Si nC −2 ( n=1–7) anions have been investigated using the density functional theory. Structural optimization and frequency analysis are performed at the level B3LYP/6-311G(d). The charged-induced structural changes in these anions have been discussed. The strong C–C bond is also favored over C–Si bonds in the Si nC −m anions in comparison with corresponding neutral cluster. Among different Si nC − and Si nC −2 ( n=1–7) anions, Si 3C −, Si 5C − and Si 2C −2 are most stable. Their stability has a decreasing tendency with the increase in the size of these clusters. 相似文献
3.
The oxidation of Cp 2MCl 2 (M= Mo, W) with perfluortriazinium tetrafluoroborate, [(FCN) 3F] +[BF 4] −, in the presence of a flouride ion acceptor (BF 3 or PF 5) in SO 2 solution yielded the cationic metallocene complexes [Cp 2MCl 2] 2+[BF 4] − or [C p2MCl 2] 2+[BF 4] −[PF 6] − (M = Mo, W), respectively. In these reactions, for the first time the perfluortriazinium cation has proved to be easy to handle and a useful oxidizer in organometallic chemistry. The oxidizer strength of three fluorotriazinium cations, [(XCN) 3F] + (X = F, Cl, H), has been computed ab initio (HF/6 − 31 + G) and calibrated on literature data which were obtained by local density functional calculations. It was anchored to its F + zero point by an experimental value for KrF +. ab]Die Oxidation von Cp 2MCl 2 mit (M = MO, W) Perfluortriaziniumtetrafluoroborat, [(FCN) 3F] +[BF 4] −, in Anwesenheit eines Fluoridionenakzeptors (BF 3 oder PF 5) führte in SO 2-Lösung zur Bildung der kationischen Metallocen-Komplexe [Cp 2MCl 2+] 2+[BF 4] 2− bzw. [Cp 2MCl 2] 2+[BF 4] − [PF 6] − (M = Mo, W). In diesen Reaktionen konnte erstmals gezeigt werden, daß Perfluortriazinium-Kationen einfach zu handhabende und nützliche Oxidationsmittel im Bereich der metallorganischen Synthese darstellen. Das (Mdationsvermögen von drei Fluorotriazinium-Kationen, [(XCN) 3F] +(X = F, Cl, H), wurde ab initio berechnet (HF/6 − 31 + G) und mit Hilfe von Literaturdaten, die mittels local density functional-Berechnungen erhalten und am experimentellen Wert von KrF + bezüglich des F + Nullpunktes verankert wurden, kalibriert. 相似文献
4.
The syntheses of Bromodisilanes Br nSi 2H 6−n and Iododisilanes I nSi 2H 6−n ( n = 1, 2, 3, 4, 5), starting from caryldisilanes Ar nSi 2H 6−n (Ar = phenyl, -naphthyl, mesityl) are reported. The 29Si-NMR-spectra of all compounds, including 29Si 29Si-coupling constants, have been measured. ZusammenfassungAusgehend von Aryldisilanen ArS2H6−n, (Ar = Phenyl, -Naphthyl, Mesityl) wurden die Bromdisilane BrnSi2H6−n, und Ioddisilane InSi2H6−n, (n = 1, 2, 3, 4, 5) synthetisiert. Die 29Si-NMR-Spektren aller Verbindungen, (eingeschlossen 29Si29Si-Kopplungskonstanten) wurden vermessen. 相似文献
5.
139La-NMR chemical shifts were measured for several anionic complexes of formulae Li(C 4H 8O 2) 3/2 [La(ν 3-C 3H 5) 4], [Li(C 4H 8O 2) 2][Cp′ nLa(ν 3-C 3]H 5) 4−n] (Cp′ = Cp(ν 5-C 5H 5); n = 1, 2 and Cp′ = Cp * (ν 5-C 5Me5); N = 1) and Li[R nLa(ν 3-C 3H 4) 4− n] (R = N(SiMe 3) 2; n = 1, 2 and R = CCsIMe 3; n = 4), as well as for neutral compounds for formulae La(ν 3-C 3H 5) 3L n (L = (C 4H 8O 2) 1.5, (HMPT) 2, TMED), Cp′ nLa(ν 3-C 3H 5) 3−n (Cp′= Cp(ν 5-Cp 5H 5), Cp *(ν 5-C 5Me 5); n = 1, 2) and La(ν 3-C 3H 2) 2X(THF) 2 X = Cl, Br, I). Typical ranges of the 139La-NMR chemical shifts were found for the different types of complex independent of number and kind of organyl groups directly bonded to lanthanum. Zusammenfassung139La-NMR-Spektroskopie wurde an einer Reihe anionischer Allyllanthanat(III)-Komplexe der Zusammensetzung
]- [La)ν3-C3H5)4, [Li(C4H8)2][Cp′nLa(ν3-C3H5)4−n(Cp′ = Cp(ν5-C5H5); n = 1, 2 und Cp′ = Cp * (ν5-C5Me5); N = 1) und Li[RnLa(ν3-C3H5)4−n (R = B(SiMe3)2; n = 1, 2 und R = CCSiMe3; n = 4 sowie neutraler Allyllanthan(III)-Komplexe der Zusammensetzung La(ν3-C3H5)3Ln (Ln = (C4H8O2)1.5, (HMPT)2, TMED), Cp′n, La(ν3-C3H5)3−n (Cp′ = Cp(ν5-C5H5), Cp * (ν5- Cp5Me5); n = 1, 2) und La(ν3-Cp3H5)2X(THF)2 (X = Cl, Br, I) durchgefürt. In Abhängikeit von der Anzahl und der Art der am Lanthan gebundenen Gruppen wurden für die verschieden Komplextypen charakteristische Resonanzbereiche ermittelt. 相似文献
6.
A calorimetric study was performed for adducts of general formula CdBr 2· nL ( n=1 and 2; L=ethyleneurea (eu) and propyleneurea (pu)). The standard molar reaction enthalpy in condensed phase: CdBr 2(c)+ nL(c)=CdBr 2· nL(c); Δ rHmθ, were obtained by reaction–solution calorimetry, to give the following values for mono- and bis-adducts: −19.54 and −34.59; −7.77 and −19.05 kJ mol −1 for eu and pu adducts, respectively. Decomposition (Δ DHmθ) and lattice (Δ MHmθ) enthalpies, as well as the mean cadmium---oxygen bond dissociation enthalpy, DCd---O, were calculated for all adducts. 相似文献
7.
The synthesis, optical properties, electrochemical properties, electronic structures and applications in electroluminescent device of three series of 1,3,4-oxadiazole derivatives, 1,4-bis[(4-methylphenyl)-1,3,4-oxadiazolyl]phenylene (OXD 1), 5,5′-di-(4-methyl)-2,2′- p-(2,5-bisalkoxyphenylene)-bis-1,3,4-oxadiazole (OXD 2–n) and 1,4-bis[(4-alkoxyphenyl)-1,3,4-oxadiazolyl]phenylene (OXD 3–n) are reported. The molecular structures of the oxadiazole compounds were confirmed by FT-IR, 1H NMR spectroscopy and elemental analysis. The optical and electrochemical properties of the compounds were investigated by UV–vis absorption and photoluminescence spectroscopy as well as cyclic voltammetry. The results show that introduction of two alkoxy groups whose electron-donating ability is stronger than that of methyl groups increases the electron density of the conjugated segment of OXD 2–n (with side-on alkoxy substituents) and OXD 3–n (with end-on alkoxy substituents), and thus leads to the absorption maximum bathochromic-shift compared to that of OXD 1. The HOMO and LUMO energy levels of the compounds studied are in the range of −2.78 to −2.89 and −5.75 to −6.20 eV. Calculations on the representative compounds by the Dmol 3 package of MS Modeling 3.0 revealed that the increase of energy levels in both OXD 2–n and OXD 3–n was due to the change of the frontier molecular orbital distribution in the central benzene ring. The light-emitting devices have been fabricated using blends of MEH-PPV and these compounds as emissive layers, among which, maximum brightness up to 11810 cd m −2 (8.5 V) has been observed, which is 40 times brighter than that with MEH-PPV. The result of the devices suggested that oxadiazole derivatives studied function well as electron-transporting materials and can be used in LEDs, and thus to enhance the efficiency of LEDs. 相似文献
8.
The epoxidation of cyclopentene with hydrogen peroxide catalyzed by 12-heteropolyacids of molybdenum and tungsten (H 3PMo 12−nW nO 40, n = 1–11), 12-tungstophosphoric acid and 12-molybdophosphoric acid combined with cetylpyridinium bromide as a phase transfer reagent was carried out in acetonitrile. Among 13 heteropolyacids investigated, catalyst of H 3PMo 6W 6O 40 showed the highest activity, giving a conversion of 60% and a selectivity of 95% in the epoxidation of cyclopentene. The fresh catalysts and the catalysts under reaction condition were characterized by UV–vis, FT-IR and 31P NMR spectroscopy, which has revealed that all of the molybdotungstophosphoric acids were degraded in the presence of hydrogen peroxide to form a considerable amount of phosphorus-containing species. The active species resulted from H 3PMo 6W 6O 40 are new kinds of phosphorus-containing species, which is different from {PO 4[WO(O 2) 2] 4} 3−. 相似文献
9.
A Doppler-based velocity selection technique has been used to measure the relative velocity dependence of the cross sections σ ji,Δ(ν r) for rotationally inelastic collisions from level ji to ji + Δν 1 = 8,22,42) in 7Li *2 A 1Σ +u)—Xe. The σ jν±2(ν r) are strongly attenuated at a smaller ν r by “torque averaging” due to molecular rotation; in contrast, for large |Δ|, σ jiΔ = ν r−n (1 n 2). An empirical intermolecular potential which reproduces these types of behavior for 3-D classical trajectories is exhibited. 相似文献
10.
The oxidation of Cp 2NbCl 2 with pure WF 6 in SO 2 solution yielded the cationic metallocene species [Cp 2NbCl 2] +[WF 6] − essentially in quantitative yield. The same reaction carried out in the presence of either equimolar amounts or a two-fold excess of HCN led to the preparation of the new niobocenium salt [Cp 2NbCl 2] 4+[WF 6] 2− which was studied by single crystal X-ray diffraction. This compound represents the first example of a structurally characterized metallocene-WF 6− complex, and crystallizes in the tetragonal system: space group, P4 12 12(No. 92), a = 11.083(8) Å, c = 48.285 (9) Å; Z = 8; R = 0.0759, RW = 0.0841. ab]Die Oxidation von Cp 2NbCl 2 mit reinem WF 6 führt in SO 2-Lösung zur Synthese von [Cp 2NbCl 2 ] +[WF 6] − in nahezu quantitativer Ausbeute. Die analoge Reaktion führt unter Anwesenheit der äquimolaren Menge oder eines zweifachen Überschusses an HCN zur Ausbildung des Niobocenium-Komplexsalzes [Cp 2NbCl 2] 4+ [WF 6] 2−[WCl 6] 2−, von dem eine Röntgenstrukturanalyse angefertigt wurde. Diese Verbindung repräsentiert den ersten structurell charakterisierten Vertreter eines Metallocen-WF 6−-Komplexes und kristallisiert im tetragonalen System: Raumgruppe P4 12 12 (Nr. 92), a = 11.083(8) Å, c = 48.285(9) Å; Z = 8; R = 0.0759, RW = 0.0841. kw]Niobium; X-ray diffraction; Oxidation; Metallocenes 相似文献
11.
Powder X-ray diffraction, 119Sn NMR spectra, and 1H NMR spin–lattice relaxation times, T1, were measured for (CH 3) nNH 4−nSnCl 3 ( n=1–4). From the Rietveld analysis, it is shown that all four compounds crystallize into deformed perovskite-type structures at room temperature. The temperature dependence of 1H T1 was analyzed in terms of the CH 3 reorientation and other motions of the whole cation. Except for the phase transition in CH 3NH 3SnCl 3, which is from monoclinic to rhombohedral at 331 K, 1H T1 was continuously changed at other phase transitions in this compound as well as in the n=2–4 compounds, suggesting that the transitions are not caused by the change of the motional state of the cation but by an instability of the [SnCl 3] nn− perovskite lattice. 相似文献
12.
A performance evaluation of Density Functional Tight Binding (DFTB) in the two-layer ONIOM method is presented in an effort to estimate DFTB effectiveness as an inexpensive low level quantum mechanical layer. Ground state geometries, geometry error, S-values and energy error for: (H 2O) x(MeOH) y, [(η 5-C 5Me nH 5−n) 2Ti] 2(μ 2, η 2,η 2-N 2), n = 4, and complexes of Cu + with tyrosine, were compared to target calculations at B3LYP level of theory for all three of the systems and second order Moller-Plesset (MP2) target level of theory for the first two systems. The calculated root-mean-square errors (RMS) of the ONIOM optimized geometries relative to the target are found to be small. The DFTB level of theory was unable to reproduce the target geometry structure for one of the isomers of tyrosine–Cu + complex, while the ONIOM combinations were able to reproduce all target structures. The absolute value of the geometry error was determined to be smaller then the corresponding energy error except for the (H 2O) x(MeOH) y system at the ONIOM(MP2/6-31G(d,p):DFTB) level of theory. The S-values were relatively small and close in value contributing to relatively small energy errors. Both method combinations ONIOM(MP2:DFTB) and ONIOM(DFT:DFTB) show similar performance compared to the corresponding target level of theory. The results also suggest that it is safe to use ONIOM(DFT:DFTB) for investigations of [(η 5-C 5Me nH 5−n) 2Ti] 2(μ 2, η 2,η 2-N 2) complexes. 相似文献
13.
The IR polarized spectra of gypsum CaSO 4·2H 2O were recorded at incidence angles of approximately 10 and 16 degrees. Band singlet or doublet was observed for the higher frequency ν 3(SO 42−) mode of Bu symmetry type, depending on polarization ( n or p). A doublet was observed for the lower frequency ν 3(SO 42−) mode of Bu symmetry type too, irrespectively of the type of polarization. In order to give an explanation for the doublets origin, a model permittivity function was constructed. Quite good agreement exists between the reflectance based on the model permittivity function and the experimentally measured one for the high-frequency doublet. The origin of the lower frequency doublet could not be explained in this way, but may be speculated to result from an Evans type interaction between a combination of a water libration and ν 2(SO 42−), with the lower frequency ν 3(SO 42−) mode. 相似文献
14.
The magnetic susceptibility has been determined for CuL n(TCNQ −) 2 (L = 2,2'-bipyridine, 1,10-phenanthroline, or ethylenediamine; n = 1 or 2), having high electric conductivity. The results show that the Cu 2+L n chelates are partially reduced to Cu 2+L n in the complexes. The equilibrium Cu 2+L n(TCNQ −) 2 Cu +L n(TCNQ −)(TCNQ o) produces conduction electrons in TCNQ columns. 相似文献
15.
The title cobalt(III) complexes have been investigated by polarized absorption and Raman spectroscopies of the single crystals. The symmetry properties of the d-electron orbitals and of the vibrational modes attributable to the Raman bands of trans(Cl 2)-[CoCl 2(NH 3) n(H 2O) 4−n]Cl complexes ( n = 2, 3, or 4) were examined to elucidated the peculiar observation that ligand substitution causes no splitting of the 15 200-cm −1 absorption band and the 250-cm −1 Raman band. Effects of replacing the NH 3 ligand with H 2O on the electronic structure, atom–atom force constants and vibrational modes of these complex ions are briefly described. 相似文献
16.
Using the temperature jump technique, the study of the kinetics of the complexing of oxomolybdate anion with malic acid has been carried out in aqueous solutions of pH 7.15–8.5 at ionic strength 0.1 M (KNO 3) and 25°'C. A reaction scheme for the formation of 1 : 1 complexes is proposed which accounts for the observed relaxation rates. The significance of the ligand deprotonation on the complexation reaction of MoO42− by a single protonated ligand, i.e. MoO42−+LHnk→MoO3(OH)Ln−2, (where n = 1 -, 2 -, etc), is analysed on the basis of a simple model. A linear correlation between the log k and the pK of the monoprotonated ligand (LH) is found for this reaction when the global process is controlled by the proton transfer from the ligand to an oxogroup, i.e. log k = a - 0.5xpK. It is found that this correlation is satisfied by MoO42− and WO42−. The experimental slopes for these oxyanions are −0.503 and −0.543 respectively, in agreement with the predictions. 相似文献
17.
High resolution vibration-rotation spectra of 13C 2H 2 were recorded in a number of regions from 2000 to 5200 cm −1 at Doppler or pressure limited resolution. In these spectral ranges cold and hot bands involving the bending-stretching combination levels have been analyzed up to high J values. Anharmonic quartic resonances for the combination levels ν 1 + mν 4 + nν 5, ν 2 + mν 4 + ( n + 2) ν 5 and ν 3 + ( m − 1) ν 4 + ( n + 1) ν 5 have been studied, and the l-type resonances within each polyad have been explicitly taken into account in the analysis of the data. The least-squares refinement provides deperturbed values for band origins and rotational constants, obtained by fitting rotation lines only up to J ≈ 20 with root mean square errors of ≈ 0.0003 cm −1. The band origins allowed us to determine a number of the anharmonicity constants xij0. 相似文献
18.
The catioanic d 1-titanocene complexes [{Cp 2Ti(L) 2+}{BPh 4−}] with L = THF (1) and pyridine (2) were very simply prepared by the reaction of [Cp 2Ti(Me 3SiCCSiMe 3)] with trimethylammoniumtetraphenylborate via a le −-oxidation of the 14e −-Cp 2Ti-unit to the paramagnetic titanium(III) complex under evolution of molecular hydrogen and the alkyne. Complex 2 is the first example of such a cationic-only neutral-ligand containing complexes without anionic ligands that has been characterized by an X-ray structure analysis. 相似文献
19.
Likely candidates for the lowest potential energy minima of (C 60) nCa 2+, (C 60) nF − and (C 60) nI − clusters are located using basin-hopping global optimisation. In each case, the potential energy surface is constructed using the Girifalco form for the C 60 intermolecular interaction, an averaged Lennard–Jones C 60–ion interaction, and a polarisation potential, which depends on the first few non-vanishing C 60 multipole polarisabilities. We find that the ions generally occupy the interstitial sites of a (C 60) n cluster, the coordination shell being tetrahedral for Ca 2+ and F −. The I − ion has an octahedral coordination shell in the global minimum for (C 60) 6I −, however for 12 n 8 the preferred coordination geometry is trigonal prismatic. 相似文献
20.
The spectrum of CD 2HF was measured by high-resolution interferometric Fourier-transform IR (FTIR) spectroscopy (apodised instrumental band with:0.004 cm −1 fwhm) between 800 and 1200 cm −1 covering the four lowest fundamentals. A complete rotational analysis using a semi-automatic assignment procedure yields accurate band centres (ν 9: 912.2028 cm −1, ν 6:964.4994 cm −1, ν 5: 1050.5104 cm −1, ν 4: 1093.8632 cm −1) and a complete set of first-order Coriolis coupling constants. The most important couplings occur between ν 9 and ν 6 (ξ a= 1.069 cm −1, ξ c= −0.3535 cm −1) and between ν 5 and ν 4 (ξ b= −0.80606 cm −1). The analysis was guided by and compared with results from our ab initio calculations for Coriolis constants and transition moments using CADPAC at TZP/MP2 level. 相似文献
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