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《Journal of Coordination Chemistry》2012,65(10):1589-1598
A straightforward synthetic route to produce tris(methacrylato)chromium(III), Cr(O2C(CH3)C=CH2)3, by reacting sodium methacrylate with an aqueous solution of CrCl3 gave a blue microcrystalline powder, insoluble in most common solvents. Electronic spectroscopy (UV-Vis), electron paramagnetic resonance (EPR), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), were employed to characterize Cr(O2C(CH3)C=CH2)3. Morphology and elemental composition of this compound were determined using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX), respectively. Spherical particles of approximately 2.5 µm in diameter were obtained. Thermal stability of the product was investigated via thermogravimetric analysis (TGA). The spectroscopic studies revealed that the coordination sphere around the chromium ion corresponds to a chelating bidentate carboxylate-Cr(III) complex. Thermal stability above 350°C, and spherical shape particles of few micrometers in diameter, suggest a potential application of this novel compound as a catalyst in oxidation reactions. 相似文献
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K. Meena K. Muthu M. Rajasekar V. Meenatchi S. P. Meenakshisundaram S. C. Mojumdar 《Journal of Thermal Analysis and Calorimetry》2013,112(2):1077-1082
Single crystals of tris(thiourea)silver(I) nitrate have been grown by slow evaporation solution growth technique from an aqueous solution at 25 °C. The single crystal X-ray diffraction study reveals that the crystal belongs to tetragonal system and cell parameters are a = b = 14.2790(4) Å, c = 24.8900(7) Å, and V = 5074.8(2) Å3. The various functional groups present in the molecule are confirmed by Fourier transformed infrared spectroscopy (FT-IR). The structure and the crystallinity of the materials were further confirmed by powder X-ray diffraction analysis. Thermogravimetric and differential thermal analysis reveal the purity of the sample and no decomposition is observed up to the melting point. The crystal is further characterized by UV–Vis and Vickers microhardness analysis. 相似文献
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《Journal of Inorganic and Nuclear Chemistry》1976,28(5):1037-1040
The thermal racemization of (+)589-Cr phen3(ClO4)3 has been examined under a variety of medium conditions. The racemization rate constant in water at 75°C, for example, is 8·5 × 10−5 sec−1, with an energy and entropy of activation of 23·5 kcal mole−1 and −10·9 e.u., respectively. The effect of acid, hydroxide, and various other added ions on the rate constant has been investigated, and the results compared with other tris-phenanthroline systems. An intramolecular twist process is considered the most probable mechanism of racemization. 相似文献
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Site-selective and narrowed luminescence and excitation spectra in the region of the (2)E <-- (4)A 2 transitions are reported for single crystals of Al(acac) 3/Cr(III) and Al(3-Br-acac) 3/Cr(III) (where acac is acetylacetonate). The R 2 line is pronounced in the brominated system and displays a comparable oscillator strength as the R 1 line. The (2)E splitting is found to be 138 cm (-1), and the (4)A 2 ground-state splitting is 1.39 cm (-1). However, in the case of the Al(acac) 3/Cr(III) system the R 2 line is not a distinct feature. We propose that vibronic coupling via a second-order Jahn-Teller effect leads to a redistribution of R 2 intensity over several vibrational sidelines. An upper limit for the R 1 line width Gamma h = 15 MHz is deduced for the Al(acac) 3/Cr(III) 1% system at 1.5 K. This line width is limited by direct and indirect electron-spinelectron-spin interactions. Accurate zero-field splittings (1.20, 1.19, 1.17 cm (-1)) for the three sites in Al(acac) 3/Cr(III) are determined and compared with previously published electron paramagnetic resonance (EPR) data. 相似文献
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P. V. Fabinskii N. V. Vologdin N. P. Samsonova V. A. Fedorov 《Russian Journal of General Chemistry》2014,84(3):552-554
Solubility data for chromium(III) and cobalt(III) tris(acetylacetonates) in water and water-tert-butanol mixtures over a wide range of temperatures and alcohol concentrations were obtained, and thermodynamic parameters of solution were calculated. The dependences of solubility on the concentration of tert-butanol have an inversion point corresponding to a change in the hydration mechanism, when the solvent structure changes from water to aqueous alcohol. 相似文献
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H. Ssekaalo 《Research on Chemical Intermediates》1990,14(1):1-14
Two precursor species have been identified as responsible for the catalyzing effect of the trichloroethanoate (TCE) anion
on the formation of tris(2,4-pentanedionato)chromium(III), Cr(acac)3. The first one is the green intermediate species (GIS) identified as tetrahydroxodecakis-μs-trichloroethanoato-trichloroethanoato-tetraaquopentachro-mium(III),
Cr5(OH)4(CCl3COO)11(H2)4. This appears to be the first pentanuclear species reported among the polynuclear alkanoato metal complexes. It reacts at
a rapid rate with the 2,4-penaanedtonate, acac, anion to produce a second precursor, the violet-green intermediate species
(VGIS) identified as bis(2,4-pentanedionato)-trichloroethanoato-aquochromium(III), Cr(C5H7O2)2(CCl3COO)(H2O). This is attacked by the remainigg acac anion to ultimaelly produce the Cr(acac)3. Thus the effect of the TCE anion in facilitating the formation of Cr(acac)3 is through the ligand coordination catalytic mechanisms. 相似文献
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《Journal of Coordination Chemistry》2012,65(4):371-378
The vanadium(III) complexes, V(S2CNMe2)3 (1) and V(S2CN i Pr2)3 (2) were prepared and characterized by analysis, IR, electronic and 1H NMR spectra. The complexes show reversible thermochromic behaviour. MM2 calculations were used to simulate the molecular structure of 1. For 2, variable temperature 1H NMR revealed hindered rotation about C–N bonds. The rotational energy barrier (38?kJ?mol?1) was obtained by molecular mechanics force-field calculations. 相似文献
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The [Tc(phen)3] (PF6)3 complex has been synthesized by ligand substitution on [Tc(tu)6]3+. The reaction proceeds quickly in aqueous solution. A pure compound is obtained with 40% yield. It was characterized by Tc elemental analysis, cerimetric titration, conductometry and electrophoresis. The corresponding spectroscopic properties (UV, Vis, IR and NMR) are also reported and discussed. 相似文献
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Treatment of [CrCl3(THF)3] with slightly more than 1 equiv of Li3(N3N) [(N3N)(3-) = ((Me3SiNCH2CH2)3N)(3-)] affords the triamidoamine complex [Cr(N3N)] (1) in 75% yield. 1 is oxidized by PhICl2, CuCl2, or AgCl to give the chromium(IV) complex [Cr(N3N)Cl] (2) in moderate yields. Alternatively, complex 2 is obtained directly from [CrCl3(THF)3] in 50% yield after treatment with 0.5 equiv of Li3(N3N). Both compounds are high-spin complexes bearing three and two unpaired electrons, respectively. Their molecular structures are described revealing a trigonal monopyramidal and trigonal bipyramidal coordination geometry of the chromium center, respectively. 相似文献
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《Journal of Coordination Chemistry》2012,65(14):2325-2333
Complexes of Cr(III) and Mn(II) with N′,N″-bis(3-carboxy-1-oxopropanyl) 2-amino-N-arylbenzamidine (H2L1) and N′,N″-bis(3-carboxy-1-oxophenelenyl) 2-amino-N-arylbenzamidine (H2L2) have been synthesized and characterized by various physico-chemical techniques. The vibrational spectral data are in agreement with coordination of amide and carboxylate oxygen of the ligands with the metal ions. The electronic spectra indicate octahedral geometry around the metal ions, supported by magnetic susceptibility measurements. The thermal behavior of chromium(III) complexes shows that uncoordinated nitrate is removed in the first step, followed by two water molecules and then decomposition of the ligand; manganese(II) complexes show two waters removed in the first step, followed by removal of the ligand in subsequent steps. Kinetic and thermodynamic parameters were computed from the thermal data using Coats and Redfern method, which confirm first order kinetics. The thermal stability of metal complexes has been compared. X-ray powder diffraction determines the cell parameters of the complexes. 相似文献
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《Journal of Inorganic and Nuclear Chemistry》1981,43(10):2265-2268
It has been demonstrated that the reaction of sodium salts of dialkyldithiocarbamates with titanium trichloride in ethanol gives a yellow-green solid, which shows a three to one stoichiometry indicating a tris coordination. Infrared spectral data indicate the complexes to be approximately of D3h symmetry, bonded through the sulfur atoms as chelates. Magnetic data show that the d1 state is retained. 相似文献
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Bharathi Alagar Muthumani Narayanan Anbalagan Krishnamoorthy 《Transition Metal Chemistry》1997,22(6):586-588
The ground- and excited-state reactivities of the [Cr- (en)3]3+ (en=1,2-diaminoethane) and [Cr(NCS)6]3− ions in a polyacrylamide
(PAA) environment are reported. The aquation kinetics of these complexes has been studied to identify the effect of added
PAA with varying molecular weight. Aquation of the complexes in aqueous acid containing PAA yielded the respective substituted
products. The macromolecule in solution was found to decrease significantly the rate of ligand replacement. Similarly, photolysis
of the cationic and anionic complexes in water–PAA mixtures revealed a decrease in aquation quantum yield. Possible explanations
for the decrease in reaction rates and quantum yields are discussed.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Zhou W Therrien JA Wence DL Yallits EN Conway JL Patrick BO Smith KM 《Dalton transactions (Cambridge, England : 2003)》2011,40(2):337-339
Chromium(III) mesityl complexes were synthesized by protonolysis of chromocene with 1,3-diisopropylimidazolium chloride or DBU hydrochloride, salt metathesis with MesMgBr, and single electron oxidation with iodine. 相似文献
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Summary Trisodium phosphate is recommended as a reagent for the microscopic detection of chromium (III). Sensitivity of the test is 6 of chromium (III) in a volume of 0.01 ml. Of particular importance is the fact that aluminum and iron (III) do not react with the reagent to form crystalline precipitates.
With 2 figures. 相似文献
Zusammenfassung Tertiäres Natriumphosphat gibt mit Chrom(III)-Lösungen eine charakteristische Fällung, in der unter dem Mikroskop rechteckige Kristalle zu erkennen sind. Weder Aluminium noch Eisen(III) gibt mit diesem Reagens einen kristallinen Niederschlag. Die Reaktion gestattet den Nachweis von 6 Chrom in 0,01 ml Lösung. Auch Quecksilber(II) gibt charakteristische Kristalle.
Résumé On recommande le phosphate trisodique comme réactif pour la recherche microscopique du chrome-III. La sensibilité de l'essai est 6 de chrome-III dans un volume de 0,01 ml. Le fait que l'alumine et le fer-III ne se combinent pas avec le réactif pour former des précipités cristallins présente une importance particulière.
With 2 figures. 相似文献