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1.
The kinetics of electron transfer from mannitol to hexacyanoferrate(III), catalyzed by osmium(VIII), has been studied in alkaline medium. The substrate order is complex, whereas it is one with respect to the catalyst. The rate is independent of the concentration of oxidant. Also, the rate increases with increasing concentration of hydroxide ion in a complex manner. A kinetic rate law corresponding to the proposed mechanism has been suggested as follows:
where [Mtol] is for mannitol. The kinetic parameters have been evaluated and the value of K1 is in agreement with the value determined spectrophotometrically. 相似文献
2.
The new polyoxotungstates
H2O (1),
· 28H2O (2) and
H2O (3) were synthesized in aqueous solution and characterized by IR and Raman spectroscopy, energy dispersive X-ray fluorescence and single-crystal X-ray analysis. The anions in 1 and 2 are the first structurally characterized sandwich-type polyoxoanions which contain trivalent manganese atoms. The manganese atoms are coordinated by four oxygen atoms of two
Keggin fragments and one water molecule, forming a square pyramid. The manganese(II) containing anions in 3 are linked via Mn–O–W-bonds, forming a two-dimensional network.Dedicated to Prof. M.T. Pope on the occasion of his retirement. 相似文献
3.
Guang Liu Melissa L. Kistler Tong Li Anish Bhatt Tianbo Liu 《Journal of Cluster Science》2006,17(2):427-443
This article reports the use of simple conductivity measurements to explore the state of small counter-ions (mostly NH 4 + and Na+) in $[\hbox{As}^{\rm III}_{12}\hbox{Ce}^{\rm III}_{16}(\hbox{H}_2\hbox{O})_{36}\hbox{W}_{148}\hbox{O}_{524}]^{76-} (\{\hbox{W}_{148}\})$ and $[\hbox{Mo}_{132}\hbox{O}_{372}(\hbox{CH}_{3}\hbox{COO})_{30} (\hbox{H}_{2}\hbox{O})_{72}]^{42-} (\{\hbox{Mo}_{132}\})$ macroanionic solutions. All the solutions are dialyzed to remove the extra electrolytes. Conductivity measurements on {(NH4)70Na6W148} and {(NH4)42Mo132} solutions at different concentrations both before and after dialysis indicate that the state of counter-ions has obvious concentration dependence. The “counter-ion association” phenomenon, that is, some small counter-ions closely associate with macroanions and move together, has been observed in both types of macroionic solutions above certain concentration. The association of counter-ions in hydrophilic macroionic solutions provides support on our previous speculation that the counter-ions might be responsible for the unique self-assembly of such macroanions into single-layer blackberry-type structures. 相似文献
4.
Israel M. Mbomekallé Fang Bian Henry Tebba Achim Müller Ira A. Weinstock 《Journal of Cluster Science》2006,17(2):333-348
Catalysis of electron transfer by a Cu-substituted wheel-type oxomolybdate cluster–anion,
, (1), is demonstrated. Data provided include aqueous-solution chemistry (stability) studies of 1 and
, (2), derivatives of the “plenary” {Mo154} anion,
, (3). Combined use of cyclic voltammetry and UV–vis spectroscopy shows that, while both 1 and 2 appear to be stable in solution at pH 0.33 (0.5 M H2SO4), 1 is more stable than 2 at pH 3 (in 0.2 M Na2SO4). Cyclic voltammetric analysis in the presence of O2 shows that 1 is an electrocatalyst for electron transfer to O2. Bulk electrolysis of 1 in the presence of O2 (ca. 1 mM) is used to assess catalyst stability under turnover conditions, and to demonstrate that the final product of electrocatalytic reduction is water, rather than H2O2. Finally, control experiments using 1, 2, and CuSO4 (no oxomolybdate-cluster present), show that catalytic activity is due to specific interaction(s) between Cu ions and the Mo142 type oxomolybdate structure of 1. 相似文献
5.
The synthesis and structural characterisation of two novel clusters, 2, and 3, are presented. They are the first examples of osmium and ruthenium clusters containing a naked
atom. 相似文献
6.
The kinetics of the environmentally important oxidation of sulfur(IV) by oxygen in acetate buffered medium in the presence
of Fe(III) and the pH range 5.27–5.70 has been studied. The results were in agreement with the rate law:
The role of iron(III) appears to be that of production of SO3− radicals in Fe(III)SO32− complex by an internal 1-equivalent redox reaction. Subsequently, a radical mechanism involving oxysulfur radicals, viz.,
SO3−, SO4−, and SO5− operates. Addition of ethanol leads to the introduction of an induction period and decrease in reaction rate, most likely
due to scavenging of SO4− radicals. The value of apparent energy of activation is 45.4 kJ mol−1. 相似文献
7.
K. Sharanabasamma Mahantesh A. Angadi Manjalee S. Salunke Suresh M. Tuwar 《Journal of solution chemistry》2012,41(2):187-199
The kinetics of oxidation of L-valine by a copper(III) periodate complex was studied spectrophotometrically. The inverse second-order
dependency on [OH−] was due to the formation of the protonated diperiodatocuprate(III) complex ([Cu(H3IO6)2]−) from [Cu(H2IO6)2]3−. The retarding effect of initially added periodate suggests that the dissociation of copper(III) periodate complex occurs
in a pre-equilibrium step in which it loses one periodate ligand. Among the various forms of copper(III) periodate complex
occurring in alkaline solutions, the monoperiodatocuprate(III) appears to be the active form of copper(III) periodate complex.
The observed second-order dependency of [L-valine] on the rate of reaction appears to result from formation of a complex with
monoperiodatocuprate(III) followed by oxidation in a slow step. A suitable mechanism consistent with experimental results
was proposed. The rate law was derived as:
- \fracd[DPC]dt = \frackK1K2K3[Cu(H2IO6)2]f3- [L -Val]f2[H3IO62 -]f[OH - ]f2.- \frac{\mathrm{d}[\mathrm{DPC}]}{\mathrm{d}t} =\frac{kK_{1}K_{2}K_{3}[\mathrm{Cu}(\mathrm{H}_{2}\mathrm{IO}_{6})_{2}]_{\mathrm{f}}^{3-} [\mathrm{L} -\mathrm{Val}]_{\mathrm{f}}^{2}}{[\mathrm{H}_{3}\mathrm{IO}_{6}^{2 -}]_{\mathrm{f}}[\mathrm{OH}^{ -} ]_{\mathrm{f}}^{2}}. 相似文献
8.
Maxim N. Sokolov Artyom L. Gushchin Dmitrii Yu. Naumov Olga A. Gerasko Vladimir P. Fedin 《Journal of Cluster Science》2005,16(3):309-318
Mechanochemical reaction of cluster coordination polymers
(Q=S, Se) with solid
leads to the cluster core excision with the formation of anionic complexes
. Extraction of the reaction mixture with water followed by crystallization gives crystalline
(main product) and
(1) (minor product). In the case of the Se cluster, the
complex could not be isolated, and the treatment of the aqueous extract with PPh3 gave
(2) in a low yield. Alternatively, it was obtained from
and
in high yield. Both 1 and 2 were characterized by X-ray structure analysis.
Dedicated to Academician I. I. Moiseev on the occasion of his 75th birthday and in recognition of his outstanding contribution
to cluster chemistry. 相似文献
9.
The acid?Cbase behavior of $\mathrm{Fe}(\mathrm{CN})_{6}^{4-}$ was investigated by measuring the formal potentials of the $\mathrm{Fe}(\mathrm{CN})_{6}^{3-}$ / $\mathrm{Fe}(\mathrm{CN})_{6}^{4-}$ couple over a wide range of acidic and neutral solution compositions. The experimental data were fitted to a model taking into account the protonated forms of $\mathrm{Fe}(\mathrm{CN})_{6}^{4-}$ and using values of the activities of species in solution, calculated with a simple solution model and a series of binary data available in the literature. The fitting needed to take account of the protonated species $\mathrm{HFe}(\mathrm{CN})_{6}^{3-}$ and $\mathrm{H}_{2}\mathrm{Fe}(\mathrm{CN})_{6}^{2-}$ , already described in the literature, but also the species $\mathrm{H}_{3}\mathrm{Fe}(\mathrm{CN})_{6}^{-}$ (associated with the acid?Cbase equilibrium $\mathrm{H}_{3}\mathrm{Fe}(\mathrm{CN})_{6}^{-}\rightleftharpoons \mathrm{H}_{2}\mathrm{Fe}(\mathrm{CN})_{6}^{2-} + \mathrm{H}^{+}$ ). The acidic dissociation constants of $\mathrm{HFe}(\mathrm{CN})_{6}^{3-}$ , $\mathrm{H}_{2}\mathrm{Fe}(\mathrm{CN})_{6}^{2-}$ and $\mathrm{H}_{3}\mathrm{Fe}(\mathrm{CN})_{6}^{-}$ were found to be $\mathrm{p}K^{\mathrm{II}}_{1}= 3.9\pm0.1$ , $\mathrm{p}K^{\mathrm{II}}_{2} = 2.0\pm0.1$ , and $\mathrm{p}K^{\mathrm{II}}_{3} = 0.0\pm0.1$ , respectively. These constants were determined by taking into account that the activities of the species are independent of the ionic strength. 相似文献
10.
Determination of the Distribution of Cobalt-Chloro Complexes in Hydrochloric Acid Solutions at 298 K
Masahito Uchikoshi 《Journal of solution chemistry》2018,47(12):2021-2038
Knowledge of the distribution of metal-chloro complexes in hydrochloric acid solutions is fundamental for understanding the anion-exchange reaction. Anion-exchange separation allows ultrahigh purification during hydrometallurgical processes. However, at present the exchange reactions are not understood in detail. A more sophisticated purification needs improvement of the anion-exchange separation process. The process is based upon anion-exchange reactions and the distribution of metal-chloro complexes. The present work deals with cobalt-chloro complexes which exhibit a beautiful deep blue color in a concentrated hydrochloric acid solution. The intensity of the absorption attributed to the deep blue color is so strong that it is hard to obtain meaningful results by factor analysis. Another absorption band was chosen to be used in factor analysis and the attempt was successful. The number of cobalt-chloro complexes in hydrochloric acid solutions was determined to be three, and the cumulative formation constants were fitted to absorption spectra decomposed by factor analysis. During the optimization of the cumulative formation constants, a modified Debye–Hückel model for estimation of the activity coefficients of \(\hbox {Cl}^{-}\) was used. It was found that there are three cobalt complexes \([\hbox {Co}^{\mathrm{II}}(\hbox {H}_{2}\hbox {O})_{6}]^{2+}\), \([\hbox {Co}^{\mathrm{II}}\hbox {Cl}(\hbox {H}_{2}\hbox {O})_{5}]^{+}\), and \([\hbox {Co}^{\mathrm{II}}\hbox {Cl}_{4}]^{2-}\), and the two cumulative formation constants were optimized such that \(\log _{10}\beta _{1} = -\,0.861\) and \(\log _{10}\beta _{4} = -\,7.40\). The geometries of the complexes are proposed by assignment of absorption bands using ligand field theory. A qualitative assessment of the relationship between the acquired distribution of cobalt-chloro complexes and the adsorption function of cobalt species from hydrochloric acid solutions to anion-exchange resin was made. 相似文献
11.
Thermal treatment in air of the organometallic polymer
(1) results in the formation of nanometer-size metal oxide particles. Cr particles in the 35–85 nm range, mostly 54 nm, immersed
in an phosphorus oxides matrix were found. ATG studies in air suggest that the formation of the nanostructures occurs in four
steps, the first involving loss of the carbonyl groups of the Cr(CO)5 fragment. The following steps involve the oxidation of the organic matter and finally the oxidation of the chromium to give
the pyrolytic product. The use of these kinds of organometallic polymers as precursors for a general and potential new route
to materials having metal/metal oxide nanostructures is discussed. 相似文献
12.
Noorjahan Begum Dennis W. Bennett G. M. Golzar Hossain Shariff E. Kabir Ayesha Sharmin Daniel T. Haworth Tasneem A. Siddiquee Edward Rosenberg 《Journal of Cluster Science》2005,16(3):413-428
Treatment of the electronically unsaturated 4-methylquinoline triosmium cluster $[\hbox{Os}_{3}\hbox{(CO)}_{9}(\upmu_3\hbox{-}\upeta^{2}\hbox{-}\hbox{C}_{9}\hbox{H}_{5} \hbox{(4-Me)N})(\upmu\hbox{-H})]$ (1) with tetramethylthiourea in refluxing cyclohexane at 81°C gave $[\hbox{Os}_{3}\hbox{(CO)}_{8}(\upmu\hbox{-}\upeta^{2}\hbox{-C}_{9}\hbox{H}_{5} \hbox{(4-Me)N})(\upeta^2\hbox{-SC}(\hbox{NMe}_2\hbox{NCH}_2\hbox{Me})(\upmu \hbox{-H})_2]$ (2) and $[\hbox{Os}_{3}\hbox{(CO)}_{9}(\upmu\hbox{-}\upeta^{2}\hbox{-C}_{9}\hbox{H}_{5}\hbox{(4-Me)N})(\upeta^1\hbox{-SC}(\hbox{NMe}_2)_2)(\upmu\hbox{-H})]$ (3). In contrast, a similar reaction of the corresponding quinoline compound $[\hbox{Os}_{3}\hbox{(CO)}_{9}(\upmu_{3}\hbox{-}\upeta^{2}\hbox{-C}_{9}\hbox{H}_{6}\hbox{N})(\upmu\hbox{-H})]$ (4) with tetramethylthiourea afforded $[\hbox{Os}_{3}\hbox{(CO)}_{9}(\upmu\hbox{-}\upeta^{2}\hbox{-C}_{9}\hbox{H}_{6}\hbox{N})(\upeta^{1}\hbox{-SC(NMe}_{2})_{2})(\upmu\hbox{-H)}]$ (5) as the only product. Compound 2 contains a cyclometallated tetramethylthiourea ligand which is chelating at the rear osmium atom and a quinolyl ligand coordinated to the Os3 triangle via the nitrogen lone pair and the C(8) atom of the carbocyclic ring. In 3 and 5, the tetramethylthiourea ligand is coordinated at an equatorial site of the osmium atom, which is also bound to the carbon atom of the quinolyl ligand. Compounds 3 and 5 react with PPh3 at room temperature to give the previously reported phosphine substituted products $[\hbox{Os}_{3}\hbox{(CO)}_{9}(\upmu \hbox{-}\upeta^{2}\hbox{-C}_{9}\hbox{H}_{5}\hbox{(4-Me)N)(PPh}_{3})(\upmu\hbox{-H)}]$ (6) and $[\hbox{Os}_{3}\hbox{(CO}_{9}(\upmu \hbox{-}\upeta^{2}\hbox{-C}_{9}\hbox{H}_{6}\hbox{N)(PPh}_{3})(\upmu\hbox{-H)}]$ (7) by the displacement of the tetramethylthiourea ligand. 相似文献
13.
Junji Furukawa Shigenori Tsuruki Jitsuo Kiji 《Journal of polymer science. Part A, Polymer chemistry》1973,11(11):2999-3004
Alternating copolymerization of butadiene with several α-olefins and of isoprene with propylene were investigated by using a mixture of VO(Acac)2, Et3Al, and Et2AlCl as catalyst. The alternating copolymerization ability of the olefins decreases in the order, propylene > 1-butene > 4-methyl-1-pentene > 3-methyl-1-butene. The study on the sequence of the copolymer of isoprene with propylene by ozonolysis reveals that the polymer chain is reasonably expressed by the sequence \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} [{\rm CH}_{\rm 2} \hbox{--} {\rm CH} \hbox{=\hskip-1pt=} {\rm C(CH}_{\rm 3}) \hbox{--} {\rm CH}_{\rm 2} \hbox{--} {\rm CH(CH}_{\rm 3}) \hbox{--} {\rm CH}_{\rm 2} \rlap{--}]_n $\end{document}. NMR and infrared spectra indicate that the chain is terminated with propylene unit, forming a structure of ?C(CH3)? CH2? C(CH3)?CH2 involving a vinylene group. 相似文献
14.
The structure and the stability of pentazolide compounds $\hbox{A}_{\it n}(\hbox{N}_5)_{\rm 6-{\it n}}^{\it q}$ (A = B, Al, Si, P, and S; n= 1–3; q = +1, 0, ?1, ?2, and ?3), as high energy-density materials (HEDMs), have been investigated at the B3LYP/6-311+G* level of theory. The natural bond orbital analysis shows that the charge transfer plays an important role when the $\hbox{A}_{\it n}(\hbox{N}_5)_{\rm 6-{\it n}}^{\it q}$ species are decomposed to $\hbox{A}_{\it n}(\hbox{N}_5)_{\rm 5-{\it n}}\hbox{N}_3^{\it q}$ and N2. The more negative charges are transferred from the N2 molecule after breaking the N5 ring, the more stable the systems are with respect to the decomposition. Moreover, the conclusion can be drawn that ${\hbox{Al}(\hbox{N}_5)_5^{2-}}$ and ${\hbox{Al}_2(\hbox{N}_5)_4^{2-}}$ are predicted to be suitable as potential HEDMs. 相似文献
15.
The title investigation shows that pyridinium hydrobromide perbromide (PHPB) induced electron transfer reaction in pentaamminecobalt(III)
complexes of α-hydroxy acids
16.
Richard D. Adams Burjor Captain Wei Fu Mark D. Smith Lei Zhu 《Journal of Cluster Science》2006,17(1):87-95
Two new compounds Pd2Os3(CO)12
, 13 and Pd3Os3(CO)12
, 14 have been obtained from the reaction of
with Os3(CO)12 at room temperature. The products were formed by the addition of two and three
groups to the Os–Os bonds of Os3(CO)12. Compounds 13 and 14 interconvert between themselves by intermolecular exchange of the
groups in solution. Compounds 13 and 14 have been characterized by single crystal X-ray diffraction analyses.Dedicated to Professor Brian F. G. Johnson on the occasion of his retirement – 2005. 相似文献
17.
Frank J. Millero J. Magdalena Santana-Casiano Melchor González-Dávila 《Journal of solution chemistry》2010,39(4):543-558
The inorganic behavior of most divalent metals in natural waters is affected by the formation of carbonate complexes. The
acidification of the oceans will lower the carbonate concentration in the oceans. This will increase the concentration of
free copper that is toxic to marine organisms. To be able to determine the effect of this acidification, reliable stability
constants are needed for the formation of copper carbonate complexes. In this paper, the speciation of Cu(II) with bicarbonate
and carbonate ions
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