Prussian-Blue-like compounds

Magnetic Properties of Prussian Blue-like Compounds ... 

One paradigm for constructing a molecule-based material that has bulk magnetic properties is that there have to be strong ferromagnetic interactions between the unpaired spins in all three directions of space. This implies a 3D network this is true for the Prussian blue-based compounds and most likely for the V(TCNE)-based materials, although the latter are notoriously amorphous. 

In the literature the term soluble Prussian blue introduced by Keggin and Miles [5] to determine the KFeFe(CN)6 compound is still widely used. However, it is important to note, that the term soluble refers to the ease with which the potassium ion can be peptized rather than to the real solubility of Prussian blue. Indeed, it can be easily shown by means of cyclic voltammetry that the stability of Prussian blue films on electrode supports is nearly independent of their saturation by potassium cations. Moreover, Itaya and coworkers [9] have not found any appreciable amount of potassium ions in Prussian blue, which makes doubtful structures like KFeFe(CN)6. Thus, the above equation fully describes the Prussian blue/Prussian white redox reaction. 

Other Papers.—Various iron species prepared by the vacuum pyrrolysis of acetyl-ferrocene-furfural resins at 400°C have been studied by Mossbauer spectroscopy. These consist of an amorphous glass-like carbon matrix containing free iron atoms, Fe+ ions, iron clusters, superparamagnetic iron, and ferromagnetic iron.333 The effect of pressure of up to 50kbar on the absorption spectra of five iron(m), two iron(n) and one mixed valence compound has been studied. In six of the compounds, but not in basic ferric acetate or soluble Prussian Blue, the observed pressure-induced bands were assigned to d-d transitions of converted iron(n) for the ferric compounds and to spin-forbidden d-d bands for the ferrous compounds. The charge-transfer band from iron(n) to iron(m) in soluble Prussian Blue showed a blue shift at pressures up to 7.2 kbar.334... 

Of course, what the students are really interested in is why thallium is poisonous. Surprisingly, thallium is toxic because it mimics potassium in the body. But why would thallium behave like potassium As we study the periodic table and chemical periodicity, there is no immediate reason to suspect that these two elements would have similar properties. A close look at the electron shell arrangement of thallium and potassium, however, reveals that both form +1 ions. Since Tl+ ions also happen to be similar in size to K+ ions, they are able to replace potassium ions in cellular processes. (Thallium poisoning is treated with a compound called Prussian blue, which binds to +1 ions and thus facilitates their removal from the body.) It is clear then that we cannot understand the toxicity of thallium without studying its atomic structure and electron distribution. But chemistry is only part of the story. The effects of thallium poisoning only make sense if the... 

An additional family of organometallic materials is the cyanometallates, which are Prussian blue analogues. These are microporous materials, similar to zeolites, with relatively large adsorption space and small access windows [237-241], These Prussian blue analogues develop zeolite-like structures based upon a simple cubic (T[M(CN)6]) framework, in which octahedral [M(CN)6]" complexes are linked via octahedrally coordinated, nitrogen-bound Tm+ ions [237], In the prototypic compound, that is, Prussian blue, specifically (Fe4[Fe(CN)6]3 14H20), charge balance with the Fe3+ ions conducts to vacancies at one-quarter of the [Fe(CN)6]4 complexes [242],... 

De Morveau explained some of his other peculiar views in articles in the Encyclopedie Supplement on Dissolution , Crystallisation , Affinity , and Hepar a hepar is a compound like liver of sulphur, of an acid, alkali, and phlogiston carbon is a compound of vegetable acid, a peculiar earth, and fixed fire pyrites is a compound of vitriolic acid, calx of iron, and fixed fire phlogisticated alkali (potassium ferrocyanide) is a compound of animal acid, alkali, and fixed fire and Prussian blue is formed by replacing the alkali by the ferruginous base and even vegetable matters are true hepars. 

Potassium ferrocyanide forms Prussian blue, Fei[Fe(CN)J with ferric salts in acid solution. This compound, like Turnbull s blue Fe8[Fe(CN) Jg, is reduced to white ferro-ferrocyanide by strong reducing agents such as sodium hydrosulfite. 

We should also add that although molecule-based materials containing 3D nets may sound like a fancy new term, such compounds found their way into chemical industry and everyday life very early on as the coordination polymers Berlin Green, [Fe(lII)Fe(III)(CN)6], Prussian Blue, K[Fe(II)Fe(lII)(CN)6], and Turnbull s Blue, K2[Fe(II)Fe(II)(CN)6], synthesised and used as pigments since the early 18 century [3]. 

Iron blue has become a widely applied synonym for Prussian blue (various blue hexacyanoferrate compounds), replacing the large number of common terms used and felt to be causing confusion (Berrie, 1997 Buxbaum, 1998). The term Prussian blue has largely been retained here in the context of historical sources as it is well established and the synonyms less likely to... 

Paris blue, along with Berlin blue and Prussian blue (qq.v.), can be found in German hterature sources of the nineteenth and early twentieth centuries. The relationship between the three terms is somewhat complex for more information, see Berlin blue. In addition to describing Paris blue as a synonym for the violet-tinted kind of Prussian blue , Terry (1893) describes three compositions based on calcined mixtures of (a) sulfur, sodium carbonate, sodium sihcate and sodium aluminate, (b) china clay, sodium sulfate, sodium carbonate, sulfur and charcoal, and (c) sodium carbonate, orpiment, gelatinous alumina hydrate , clay and sulfur these appear likely to form ultramarine-related compounds (q.v.). 

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