共查询到20条相似文献,搜索用时 31 毫秒
1.
W. A. Prütz 《Monatshefte für Chemie / Chemical Monthly》1997,128(8-9):737-748
Summary HOCl reacts with Fe(CN)
6
4–
to generate an intermediate, presumably FeCl(CN)
6
3–
, which exhibits a weak absorption around 282 nm and decays simultaneously with the formation of Fe(CN)
6
3–
. When decreasing the HOCl/Fe(CN)
6
4–
concentration ratio fromR>1 toR<1, a drastic change in the kinetics of the oxidation is observed. Depending onR, the intermediate obviously oxidizes either Fe(CN)
6
4–
or HOCl. AtR1, a further intermediate appears which also precedes the oxidation and absorbs strongly around 360 nm. The intermediates detected may represent reactive high oxidation states of iron (Fe(IV) and Fe(VI)). HOCl induced oxidation of Fe(CN)
6
4–
is activated catalytically by Br–, I–, and N
3
–
, obviously due to generation of stronger oxidants (HOBr, HOI, and ClN3), but oxidation is efficiently inhibited by CN– and NCS–.
Mechanismen der Oxidation von K4Fe(CN)6 durch Hypochlorsäure und katalytische Aktivierung durch Azid, Bromid und Iodid
Zusammenfassung HOCl reagiert mit Fe(CN) 6 4– unter Bildung eines Intermediats, vermutlich FeCl(CN) 6 3– , das bei 282 nm eine schwache Absorption aufweist und parallel zum Erscheinen von Fe(CN) 6 3– verschwindet. Man beobachtet eine drastische Änderung in der Oxidationskinetik, wenn das HOCl/Fe(CN) 6 4– Konzentrationsverhältnis vonR>1 zuR<1 verändert wird. In Abhängigkeit vonR wird offenbar entweder Fe(CN) 6 4– oder HOCl durch das Intermediat oxidiert. FürR1 erscheint ein weiteres Intermediat mit einer starken Absorptionsbande bei 360 nm, das ebenfalls der Oxidation vorangeht. Bei den beobachteten Intermediaten handelt es sich vermutlich um reaktive höhere Oxidationsstufen des Eisens (Fe(IV) und Fe(VI)). Die HOCl-induzierte Oxidation von Fe(CN) 6 4– wird einerseits durch Br–, I– und N 3 – katalytish aktiviert (offenbar infolge der Bildung stärkerer Oxidantien wie HOBr, HOI und ClN3), andererseits durch CN– und NCS– effektiv inhibiert.相似文献
2.
Trigonal Crystallizing Metal(II) Hexacyanoferrates(II) M2II[Fe(CN)6] According to X-ray powder diagrams, Ca2[Fe(CN)6], Cd2[Fe(CN)6], Zn2[Fe(CN)6] · 2 H2O, Pb2[Fe(CN)6] and the firstly described compounds Zn2[Fe(CN)6] · 2 NH3 and Sn2[Fe(CN)6] crystallize trigonal containing one formula unit in the unit cell. Ca2[Fe(CN)6] and Cd2[Fe(CN)6] are belonging to the space group D—P3 1m, the other compounds to D—P3 m1. The latters are described as coordination polymers with a coordination number 4 for Zn and 3 for Sn and Pb, respectively. 相似文献
3.
M. V. Ryzhkov T. A. Denisova V. G. Zubkov L. G. Maksimova 《Journal of Structural Chemistry》2000,41(6):927-933
This paper presents a cluster–DV study of the electronic structure of a large fragment of the crystal lattice of a new compound Pb2Fe(CN)6 having a trigonal structure. The electronic energy spectrum and electron density distribution between Fe–C, C–N, and Pb–N are discussed. 相似文献
4.
《Solid State Sciences》2001,3(3):361-367
The crystal structure of Pb2Fe(CN)6 and Sn2Fe(CN)6 has been first determined and refined using the Rietveld method with combined CuKα1 X-ray and constant-wavelength neutron powder diffraction data in space group P-3 (147, Z=1). The unit cell constants are a=7.1346(1) and 7.1805(1) Å, c=5.4531(2) and 5.3639(1) Å, respectively. The compounds are layered, groups of three nearest [Fe(CN)6]4−-complexes are joined to layers by means of Pb or Sn atoms. The same Pb or Sn atoms (c.n.=3+3) joint three nearest complexes from the next layer. The jointing goes through ‘nitrogenlead(tin)nitrogen’ bonds. 相似文献
5.
Summary The kinetics and mechanism of the system [FeHIDA-(OH)2]–+5CN–[Fe(CN)5OH–+HIDA2–+OH– (HIDA=N-(2-hydroxyethyl) (iminodiacetate) at pH=9.5±0.02, I=0.1 M and at 25±0.1°C have been studied spectrophotometrically at 395 nm (
max of [Fe(CN)5OH]3–]. The reaction has three distinguishable stages; the first is formation of [Fe(CN)5OH]3–, the second is conversion of [Fe(CN)5OH]3– into [Fe(CN)6]3–, and last is the reduction of [Fe(CN)6]3– to [Fe(CN)6]4– by the HIDA2– released in the first stage. The first stage shows variable-order dependence on cyanide concentration, unity at high cyanide concentration and zero at low cyanide concentration. The second stage exhibits first-order dependence on the concentration of [Fe(CN)5OH]3– as well as on cyanide. The reverse reaction between [Fe(CN)5OH]3– and HIDA2– is first-order in each of these species and inverse first-order in cyanide. On the basis of forward and reverse rate studies, a five-step mechanism has been proposed for the first stage. The first step involves a slow loss of one OH–, by a cyanide-independent path. 相似文献
6.
Vladimir A. Naslusov Anatoly V. Kondratenko Konstantin M. Neyman Lev N. Mazalov 《Theoretical chemistry accounts》1986,70(6):429-441
The electronic structure of the hexacyano complexes [Fe(CN)6]4– and [Fe(CN)6]3– as clusters of the cyanide complex salts has been calculated by the SCF XSW method. Theoretical photoelectron, X-ray emission and absorption spectra have been constructed. The contribution of the resonance emission to the X-ray emission spectra has been estimated. On the basis of detailed comparison of the theoretical and experimental spectra an assignment of the fine structure of the spectra has been proposed. 相似文献
7.
Yüksel Tufan Nurcan Karacan Ümmühan Özdemr 《Journal of inclusion phenomena and macrocyclic chemistry》2001,40(4):275-278
Four new Hofmann-type clathrates of the form M(bpa)2Ni(CN)4· 2m-xylene (M = Mn , Fe , Co and Ni; bpa = 1,2-bis(4-pyridyl)ethane) have been synthesized and characterized by vibrational spectroscopy. The M(bpa)2Ni(CN)4 (M = Fe and Co) host structure is similar to the classical Hofmann-type host framework composed of layers of a two dimensional catena-metal tetra--cyanonickelate(II) network, but in M(bpa)2Ni(CN)4 (M = Mn and Ni), the Ni(CN)4 moiety behaves as a bidentate –[NC-Ni(CN)2-CN–]– unit in the host framework. 相似文献
8.
Summary The kinetics and mechanism of the system: [FeL(OH)]2–n + 5 CN– [Fe(CN)5(OH)]3– + Ln–, where L=DTPA or HEDTA, have been investigated at pH= 10.5±0.2, I=0.25 M and t=25±0.1 C.As in the reaction of [FeEDTA(OH)]2–, the formation of [Fe(CN)5(OH)]3– through the formation of mixed ligand complex intermediates of the type [FeL(OH)(CN)x]2–n–x, is proposed. The reactions were found to consist of three observable stages. The first involves the formation of [Fe(CN)5(OH)]3–, the second is the conversion of [Fe(CN)5(OH)]3– into [Fe(CN)6]3– and the third is the reduction of [Fe(CN)6]3– to [Fe(CN)6]4– by oxidation of Ln– The first reaction exhibits a variable order dependence on the concentration of cyanide, ranging from one at high cyanide concentration to three at low concentration. The transition between [FeL(OH)]2–n and [Fe(CN)5(OH)]3– is kinetically controlled by the presence of four cyanide ions around the central iron atom in the rate determining step. The second reaction shows first order dependence on the concentration of [Fe(CN)5(OH)]3– as well as on cyanide, while the third reaction follows overall second order kinetics; first order each in [Fe(CN)6]3– and Ln–, released in the reaction. The reaction rate is highly dependent on hydroxide ion concentration.The reverse reaction between [Fe(CN)5(OH)]3– and Ln– showed an inverse first order dependence on cyanide concentration along with first order dependence each on [Fe(CN)5– (OH)]3– and Ln–. A five step mechanism is proposed for the first stage of the above two systems. 相似文献
9.
Zusammenfassung Auf Grund spektrophotometrischer und konduktometrischer Messungen wurden folgende Koordinationsformen des Eisen(III)-ions mit Azid-, Rhodanid-, Cyanid- und Fluoridionen in Dimethylsulfoxid festgestellt: [Fe(N3)4]–, [Fe(SCN)6]3–, [Fe(CN)2]+, Fe(CN)3, [Fe(CN)4]–, [FeF2]+, [FeF4]–.
Mit 4 Abbildungen 相似文献
By means of spectrophotometric and conductometric measurements the following coordination forms of iron(III) with azide-, thiocyanate-, cyanide- and fluoride ions were found in dimethyl sulfoxide: [Fe(N3)4]–, [Fe(SCN)6]3–, [Fe(CN)2]+, Fe(CN)3, [Fe(CN)4]–, [FeF2]+, [FeF4]–.
Mit 4 Abbildungen 相似文献
10.
Summary The kinetics and mechanism of exchange of HPDTA in [Fe2HPDTA(OH)2] with cyanide ion (HPDTA=2-hydroxytrimethylenediaminetetraacetic acid) was investigated spectrophotometrically by monitoring the peak at 395 nm (
max of [Fe(CN)5OH]3– at pH=11.0±0.02,I=0.25m (NaClO4) at ±0.1°C).Three distinct observable stages were identified; the first is the formation of [Fe(CN)5OH]3–, the second the formation of [Fe(CN)6]3– from it and the third the reduction of [Fe(CN)6]3– to [Fe(CN)6]4– by HPDTA4– released in the first stage.The first stage follows first-order kinetics in [Fe2HPDTA(OH)2] and second-order in [CN–] over a wide range of [CN–], but becomes zero order at [CN–]<5×10–2
m. We suggest a cyanide-independent dissociation of [Fe2HPDTA)(OH)2] into [FeHPDTA(OH)] and [Fe(OH)]2+ at low cyanide concentrations and a cyanide-assisted rapid dissociation of [Fe2HPDTA(OH)2] to [FeHPDTA(OH)(CN)]3– and [Fe(OH)]2+ at higher cyanide concentrations. The excess of cyanide reacts further with [FeHPDTA(OH)(CN)]3– finally to form [Fe(CN)5OH]3–.The reverse reaction between [Fe(CN)5OH]3– and HPDTA4– is first-order in [Fe(CN)5OH]3– and HPDTA4–, and exhibits inverse first-order dependence on cyanide concentration.A six-step mechanism is proposed for the first stage of reaction, with the fifth step as rate determining. 相似文献
11.
Chimatadar Shivamurti A. Koujalagi Sangappa B. Nandibewoor Sharanappa T. 《Transition Metal Chemistry》2002,27(1):62-68
The oxidation of PdII by Fe(CN)
6
3–
has been studied in 55% MeCO2H–H2O containing 4.0 mol dm–3 HCl, the oxidation being made possible by altering redox potentials. The active species of PdII and Fe(CN)
6
3–
are PdCl
3
–
and H2Fe(CN)
6
–
, respectively. A possible mechanism is proposed and verified, and the reaction constants involved have been evaluated. 相似文献
12.
Gerasimenko A. V. Merkulov E. B. Tkachenko I. A. Kavun V. Ya. Goncharuk V. K. Sergienko V. I. 《Russian Journal of Coordination Chemistry》2002,28(12):839-842
The crystal structure of SnZrF6 is determined. The compound is synthesized by slow crystallization from a melted mixture of SnF2 and ZrF4 (2 : 1). The crystals are monoclinic: a = 6.6119(5), b = 5.2503(5), c = 6.9929(6) Å, = 114.239(4)°, space group P2/n, Z = 2. The structure is layered. The layers are formed from the chains of edge-sharing, eight-vertex zirconium polyhedra and Sn2+ cations. The Zr–F and Sn–F bond lengths in the layer vary from 2.309(1) to 2.269(1) Å and from 2.186(1) to 2.361(1) Å, respectively. The layers are linked by intermolecular Sn–F bonds with lengths of 2.868(1) and 2.871(1) Å. 相似文献
13.
Yuan Ai-Hua Lu Lu-De Shen Xiao-Ping Chen Li-Zhuang Yu Kai-Bei 《Transition Metal Chemistry》2003,28(2):163-167
A cyanide-bridged FeIII–FeII mixed-valence assembly, [FeIII(salen)]2[FeII(CN)5NO] [salen = N,N-ethylenebis(salicylideneiminato)dianion], prepared by slow diffusion of an aqueous solution of Na2[Fe(CN)5NO] · 2H2O and a MeOH solution of [Fe(salen)NO3] in an H tube, has been characterized by X-ray structure analysis, i.r. spectra and magnetic measurements. The product assumes a two-dimensional network structure consisting of pillow-like octanuclear [—FeII—CN—FeIII—NC—]4 units with dimensions: FeII—C = 1.942(7) Å, C—N = 1.139(9) Å, FeIII—N = 2.173(6) Å, FeII—C—N = 178.0(6)°, FeIII—N—C = 163.4(6)°. The FeII—N—O bond angle is linear (180.0°). The variable temperature magnetic susceptibility, measured in the 4.8–300 K range, indicates the presence of a weak intralayer antiferromagnetic interaction and gives an FeIII–FeIII exchange integral of –0.033 cm–1. 相似文献
14.
Nagornyi O. V. Kolyshkin A. S. Vol'khin V. V. 《Russian Journal of Applied Chemistry》2003,76(8):1238-1241
Fe(CN)6
3
- and Fe(CN)6
4
- anions are sorbed from aqueous solutions of their potassium and cesium salts on -Ni(OH)2 by the mechanism of anion exchange with hydroxy groups. Alkali metal cations (K+, Cs+) are also partly sorbed on nickel(II) hydroxide in the form of anionic complexes (K,Cs)
z
Fe(CN)6
(n - z)-, where n = 3 or 4 (0 < z < n). The chemical composition of the new phase appearing in contact of nickel(II) hydroxide with aqueous potassium and cesium hexacyanoferrates(II, III) was determined by X-ray phase analysis and IR spectroscopy. 相似文献
15.
Summary Four kinds of novel CN-bridged NiII-FeIII complexes, [NiLn(NC)Fe(CN)5] –, have been synthesized and characterized by elemental analysis, i.r. and u.v.-vis. spectral analysis, and magnetic moments. The formation of cyanide bridges is evident from the i.r. and u.v.-vis. spectra by the appearance of v(CN) shifts and changes in
max with respect to the mononuclear parent complex [Fe(CN)6]3–. The magnetic properties indicate the existence of magnetic spin interactions between NiII and FeIII through the cyanide bridge. 相似文献
16.
The kinetics of RuIII catalyzed reduction of hexacyanoferrate(III) [Fe(CN)6]3–, by atenolol in alkaline medium at constant ionic strength (0.80 mol dm–3) has been studied spectrophotometrically, using a rapid kinetic accessory. The reaction between atenolol and [Fe(CN)6]3– in alkaline medium exhibits 1:2 stoichiometry [atenolol:Fe(CN)6
3–]. The reaction showed first order kinetics in [Fe(CN)6]3– concentration and apparent less than unit order dependence, each in atenolol and alkali concentrations. Effect of added products, ionic strength and dielectric constant of the reaction medium have been investigated. A retarding effect was observed by one of the products i.e., hexacyanoferrate(II). The main products were identified by i.r., n.m.r., fluorimetric and mass spectral studies. A mechanism involving the formation of a complex between the atenolol and the hydroxylated species of ruthenium(III) has been proposed. The active species of oxidant and catalyst were [Fe(CN)6]3–and [Ru (H2O)5OH]2+, respectively. The reaction constants involved in the mechanism were evaluated. The activation parameters were computed with respect to the slow step of the mechanism, and discussed. 相似文献
17.
Two cyano-bridged assemblies, [FeIII(salpn)]2[FeII(CN)5NO] (1) and [FeIII (salpn)]2[NiII(CN)4] (2) [salpn = N, N-1,2-propylenebis(salicylideneiminato)dianion], have been prepared and structurally and magnetically characterized. In each complex, [Fe(CN)5NO]2– or [Ni(CN)4]2– coordinates with four [Fe(salpn)]+ cations using four co-planar CN– ligands, whereas each [Fe(salpn)]+ links two [Fe(CN)5NO]2– or [Ni(CN)4]2– ions in the trans form, which results in a two-dimensional (2D) network consisting of pillow-like octanuclear [—MII—CN—FeIII—NC—]4 units (M = Fe or Ni). In complex (1), the NO group of [Fe(CN)5NO]2– remains monodentate and the bond angle of FeII—N—O is 180.0°. The variable temperature magnetic susceptibilities, measured in the 5–300 K range, show weak intralayer antiferromagnetic interactions in both complexes with the intramolecular iron(III)iron(III) exchange integrals of –0.017 cm–1 for (1) and –0.020 cm–1 for (2), respectively. 相似文献
18.
Francesco Malatesta Franco Bruni Nicolangelo Fanelli Sara Trombella Roberto Zamboni 《Journal of solution chemistry》2000,29(5):449-461
The activity coefficients of K3[Co(CN)6], Mg3[Co(CN)6]2, and Ca3[Co(CN)6]2,are examined. The results highlight close similarity with the correspondinghexacyanoferrate (III) salts. On dilution, K3[Co(CN)6], like K3[Fe(CN)6], approachesthe limiting law from the upper side, while Mg3[Co(CN)6]2 and Ca3[Co(CN)6]2tend to the limiting law from the opposite side, like Mg3[Fe(CN)6]2,Ca3[Fe(CN)6]2, Sr3[Fe(CN)6]2, and Ba3[Fe(CN)6]2. Both kinds of behavior agreewith theory for a model of hard spheres bearing electric charges +1 and –3 or+2 and –3, respectively. The paramater values of the Pitzer equation for activityand osmotic coefficients are reported. 相似文献
19.
The rate of the reaction 2Fe(CN)
6
4–
+S
2
O
8
2–
2Fe(CN)
6
3–
+ 2SO
4
2–
in the presence of Group IIA cations in aqueous solution has been studied over the range of ionic strength from 0.006 to 0.20 M at three temperatures between 5 and 35°C. The results are interpreted by means of the Brønsted(2) equation, and it is concluded that the actual reacting species are MFe(CN)
6
2–
, and S2O
8
2–
, where M is a Goup IIA metal. The contribution from the nonion-paired species seems to be negligibly small. Rate constants and activation parameters are reported for the observed reaction pathway, and these are compared with those for the same reaction carried out in the presence of alkali metal cations. The results are considered in terms of a mechanism involving cation bridging, and qualitatively this model is consistent with the trends in the results. 相似文献
20.
Shivamurti A. Chimatadar Manjalee S. Salunke Sharanappa T. Nandibewoor 《Transition Metal Chemistry》2004,29(7):743-750
The kinetics of oxidation of AsIIIby Fe(CN)6
3– has been studied spectrophotometrically in 60% AcOH–H2O containing 4.0moldm–3HCl. The oxidation is made possible by the difference in redox potentials. The reaction is first order each in [Fe(CN)6
3–] and [AsIII]. Amongst the initially added products, Fe(CN)6
4– retards the reaction and AsVdoes not. Increasing the acid concentration at constant chloride concentration accelerates the reaction. At constant acidity increasing chloride concentration increases the reaction rate, which reaches a maximum and then decreases. H2Fe(CN)6
–, is the active species of Fe(CN)6
3–, while AsCl5
2– in an ascending portion and AsCl2
+ in a descending portion are considered to be the active species of AsIII. A suitable reaction mechanism is proposed and the reaction constants of the different steps involved have been evaluated. 相似文献