Ferrous cyanide

Ferrocyanid, n. ferrous cyanide, iron(II) cyanide ferrocyanide. 

Another example of the correlation between the isomer shift and covalent bonding properties is n-backbonding. The observed isomer shift of ferrous cyanides [Fe(ll)(CN)5X"] " [24] becomes more negative with increasing... 

Sometimes it so happens that crystals of a new salt are formed when solutions of two simple salts are mixed and the mixed solution is evaporated. The salt thus obtained is a distinct chemical substance in the solid state as well as in solution. In aqueous solution, it does not dissociate into all the simple ions of the salts it is obtained from, but yields complex ions along with the simple ions. Such a salt is known as a complex salt. A characteristic feature of complex salts is that in these the constituents retain their separate entities both in the solid state and in solution. Potassium ferrocynide, K4Fe(CN)6, is a complex salt and is obtained on mixing the solution of a ferrous salt with an excess of potassium cyanide solution. From its composition [Fe(CN)2,4 KCN], it appears to be a mixture of ferrous cyanide and potassium cyanide in the ratio of 1 4, and is thus taken to be an ordinary double salt. This representation of the compound is, however, not satisfactory since it responds neither to tests for Fe2+ ions nor to those for CN ions but does respond to tests for K+ ions and tetravalent Fe(CN)Jj ions. The ionization reaction of the complex salt cited in the present example can be represented as ... 

The potassium atoms are attached to the ring itself and not to iron, so that isomerism becomes possible depending on the positions assumed by these atoms. The meta- and para-salts are more evenly balanced and may be expected to show greater stability the ortho-salt, is the double salt, 4KCN.Fe(CN)2, and in view of the instability of ferrous cyanide this complex may not be stable. Also, either the meta- or the para- compound may be easily transformed into the nitro-prussidc. 

The practice of assuming an increased valency for nitrogen when ammonia unites with hydrogen chloride, says A. Werner, if consistently carried out, would make antimony tervalent in antimony trichloride, and quinquevalent in SbCl3.KCl, etc. Bivalent iron in ferrous cyanide, FeCy2, would become decivalent in potassium ferrocyanide, K4FeCy6. J. Piccard and J. H. Dardel, and P. Pfeiffer discussed this subject. 

On the basis of the foregoing generalization, it is reasonable to postulate that the simple transition metal cyanides with six or less d electrons will adopt the Prussian blue structure. However, metal cyanides with seven or more d electrons will crystallize in less symmetric structures. At the present there are insufficient data to thoroughly check this proposal, but the few known structures lend support to the idea. For example, ferrous cyanide (ferrous ferrocyanide) and ferric cyanide (ferric ferri-cyanide) crystallize with the Prussian blue structure while nickel and zinc cyanides do not. 

Iron blue pigment is the international standard name (ISO 2495) for ferrous cyanide blue pigments of various compositions which are also known as Berlin Blue, Turnbull s Blue, Prussian Blue, Vossen Blue , Milori Blue, Parisian Blue, French Blue, China Blue, Bronze Blue, Steel Blue, Ink Blue, etc. 

The constitution of ferrous cyanide is discussed by Browning, who suggests that it is really an isocyanide, for, when warmed with potassium... 

Robiquet (see Dammer, Handbuch der anorganischen Chemie, 1893, III, 364) believed that ferrous cyanide resulted when Prussian blue was reduced by hydrogen sulphide Hofmann (Annalen, 1907, 352, 54) shows that this cannot be correct. 

The weakness of this formula lies in the fact that the only available evidence on the subject points to the conclusion that the iron is attached directly to nitrogen, and not to the carbon as here represented, ferrous cyanide having the isocyanic structure.2... 

In an analogous manne three isomerides are, theoretically, possible for potassium ferricyamdc, K3Fe(CN)6, in vhich the central iron atom is trivalent. All of these cyclic schemes are m harmony with the isocyamc structure of ferrous cyanide, They also serve to explain why the potassium ions are ionisable, whereas the iron atom, bound within the centre of the shell, constitutes part of the negative radicle. 

Hydrogen ferrocyanide is soluble in water and possesses a strong acid reaction. The solution decomposes on boiling, evolving gaseous hydrogen cyanide, and yielding a white precipitate of ferrous cyanide. Thus —4... 

Heated in the absence of air to 300° C. a pale yellow powder (ferrous cyanide) is obtained,1 hydrogen cyanide being evolved.2... 

Iron and Cyanogen—Ferrous Cyanide—Constitution of Ferro- and Fern-cyanides —Ferrocyamdes—Cuproferrocyanides—Double Salts with Mercunc Cyanide —Ferricyamdes—Iron Derivatives of Ferro- and Ferri-cyanides—Prussian Blue. 

A classical example of how bonds are formed refers to potassium hexa-cyanoferrate(n) [K4Fe(CN)6], made by mixing colourless potassium and ferrous cyanides together to form a brownish-yellow coloured product which lacks the lethal poisonous properties of potassium cyanide. A century ago, Werner explained many such phenomena by his principles that ... 

Belleli et al. (111) have utilized RSSF to investigate the influence of the distal histidine residue on the dissociation of cyanide from ferrous (Fe2+) myoglobin. Rapid mixing of a ferric-cyanide complex with dithionite results in the rapid formation of a spectroscopically distinguishable ferrous-cyanide complex, which slowly decomposes to yield reduced myoglobin and HCN. In this study, the RSSF spectral changes and kinetic time courses of both horse heart and sperm... 

T.3.2.3. Cyanide The depression of pyrite by cyanide is considered to invoke formation of an iron cyanide complex. The electrochemical reaction for the formation of a ferrous cyanide complex is shown below ... 

SYNTHESIS OF FERROUS CYANIDE COMPLEXES INSIDE ZEOLITE Y... 

We report the preparation of ferrous-cyanide complexes in the zeolite framework. The treatment of Fe(II)-Y zeolite with a methanolic solution of cyanide ions results in the formation of two anionic species distributed into the cavities. The preliminary results of thermal stability and characterization of genarated complexes are reported. 

The synthesis procedure of ferrous-cyanide complexes in the zeolite Y was adopted from earlier studies [8,9]. Generally, the method involes the treatment of a ferrous ion exchanged NaY zeolite with methanolic solutions of cyanide. 

The zeolite Y containing ferrous cyanide species were gradually heated under a vacuum up to 400C and the IR spectra recorded. Heating the Fe(CN)-Y(l) sample up to 200C (figure 2, spectrum A) does not affect the IR band positions, except for the shift of the major band from 2044 to 2056 cm. ... 

Discussion Complex salts are formed as the result of the union of two salts. They differ from double salts in that they do not break down in solution into the ions of the salts from which they are formed. Potassium ferrocyanide is an example of a complex salt. It can be prepared by dissolving ferrous cyanide in a solution of potassium cyanide ... 

After many years of development, the U.S. Department of Defense-funded project WP-1460 [67] was made a significant progress. In 2007, Idaho National Laboratory completed a continuous process of electrochemical synthesis of the key intermediate 2,2-nitroethyl potassium (KDNE) of DNPOH in the laboratory [68] from nitroethane. It was believed that the electrochemical process to produce DNPOH could reduce more than 92 % of the waste, carbide or nickel alloy rods was used as electrodes instead of silver rods according to the U.S. patent [69]. With different voltages, anode oxidizes inactive chemical intermediates (such as ferro-cyanide ion) into active intermediates or oxidant (such as iron cyanide ion). Oxidants and nitro compounds react with nitrite ions to form a gem-dinitro product. Anode can oxidize ferrous cyanide continuously to produce lively iron cyanide ions, thus to provide enough iron cyanide ions for reaction. The scheme of synthesis is shown in Fig. 4.6. 

TH" attached to poly(V-methylolacrylamide-co-acrylic acid), etc., was coated on a Pt electrode. Its cyclic voltammogram showed the formation of a complex between the coated dye and ferric/ferrous cyanide present in the solution. When the electrode is illuminated in a Fe aqueous solution, cathodic polarization at the coated electrode is observed, in contrast to the bare electrode dipped in a mixture of TH and Fe ", which gave an anodic response at the electrode" . It was proposed that, for the polymer-coated electrode, the excited states of TH and Fe " form a complex, which is stabilized by the polymer network and accepts an electron from the electrode. A flash photolysis study showed the formation of such a complex... 

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