Iron cyanide compounds

Iron in both the +2 and +3 valence states forms several stable hexacoordi-nated octahedral complexes with cyanide (CN ) ion, known as ferrocyanide or hexakiscyanoferrate(4—), [Fe(CN)6] and ferricyanide or hexakiscyanofer-rate(3-), [Fe(CN)6]3-, respectively. The simple iron(II) cyanide, Fe(CN)2 is unstable and all iron cyanide compounds known are coordination complexes. 

Many people, both experts and laymen, rely good-naturedly upon the findings of the Jan Sehn Institute for Forensic Research in Cracow, i.e., the study published in 1994 by Prof. Markiewicz and colleagues. These Polish scientists, however, tested their samples with analytical methods that were unable to detect stable iron cyanide compounds. They did this because they could not imagine how such stable iron cyanide compounds could form. It is, of course, no shame to fail to... 

In the dpa notice it was stated that cyanide compounds will last in stone only under absolute conservation conditions , but in contrast to that, in the masonry of the cases of interest here and investigated in detail in this report, the disinfestation chambers of Auschwitz, hydrogen cyanide formed extremely long-lasting iron cyanide compounds of the Iron Blue type. See the arguments given above for proof of this. 

Many exterminationists rely heavily on the results of the Krakow Institute of Forensic Research, i.e., the work of Markiewicz and colleagues as pubhshed in 1994. These Poles have conducted their analyses with a method which is not able to detect iron cyanide compounds. They did this because they allegedly didn t understand how such compounds could possibly form 11... 

It is likely that under these conditions hydrogen sulfide does not react at all with iron oxide and that reactions 9-10 and 9-11 are the only ones occurring. The iron, which in most cases is added to the solution as soluble iron sulfate, serves only to replenish the iron-cyanide compounds lost with the sulfur. 

Cyaneisen, n. iron cyanide, -kalium, n. potassium ferrocyanide, -verbindungt /. iron cyanogen compound, specif, a ferrocyanide. 

Cyanide compounds are useful to society in terms of their key role in synthetic and industrial processes, for certain fumigation and agricultural uses, and for some therapeutic applications (Ballantyne and Marrs 1987). Cyanides are present in effluents from iron and steel processing plants, petroleum refineries, and metal-plating plants, and constitute a hazard to aquatic ecosystems in certain waste-receiving waters (Smith et al. 1979) and to livestock (USEPA 1980 Towill et al. 1978). Cyanide serves no useful purpose in the human body, yet it is present in our food, air, and water (Becker 1985). 

Manganese(III) is a strong oxidizing agent and is subject to disproportionation as well. Complexes of Mn(III) are also relatively unstable with the exception of [Mn(CN)6]3, which forms readily upon exposure of a solution of manganese(II) and cyanide to air. A few iron(IV) compounds are known. 

To 1 g sample, add 100 mL of 10% caustic soda solution and stir for 12 h. (This treatment is required only if iron cyanides are suspected to be present in the sample.) After this, adjust the pH to less than 8.0 with 1 1 H2S04. Add about 0.2 g sulfamic acid to avoid nitrate/nitrite interference. This is followed by addition of 25 mg lead carbonate (to prevent interference from sulfur compounds). The mixture is distilled and collected over NaOH solution. This distillate is analyzed for CN by colorimetric, titrimetric, or ion-selective electrode method. 

The reaction products of interest to us in this respect are the salts of hydrogen cyanide, called cyanides,314 in particular, the iron cyanide group, formed by a compound of iron and cyanide. Iron occurs universally in nature. It is iron which gives brick its red color, sand its ochre color, and clay its color ranging from yellowish to reddish-brown. More precisely, we are speaking of iron oxide, popularly known as rust . Basically, all walls consist of at least 1% rust, as a result of sand, gravel, clay, and cement, of which the wall is constructed. 

Iron Blue is considered one of the least soluble cyanide compounds, which is the precondition for its widely-varied application as a pigment.362 The literature flatly refers to Iron Blue as insoluble .363... 

Color Image 2 Exterior southwest wall of the Zyklon B disinfestation wing of BW 5b in the Auschwitz-Birkenau camp a deep blue discoloration, caused by cyanide compounds which penetrated the entire wall over the decades since WWII and formed the blue pigment with iron compounds contained in cement and bricks. This pigment is unaffected by 55 years of weathering. 

An important environmental issue is the fate of cyanide. HCN, if spilled, evaporates quite readily. That which does not evaporate is soon decomposed or rendered nonhazardous by complexing with iron in the soil, by biological oxidation or by degradation from photolysis129. Several methods for treatment and disposal of cyanide compounds are described in references 129 and 133. 

Fig. 24-1. Iron-Cyanide Framework in Prussian Blue and Related Compounds...

Cyanides (CN -compounds) are hydrogen cyanide (hydrogen cyanide, HCN) salts. In this case, specifically ferro(III)-ferri(II)-cyanide, but one can expect to find all sorts of iron cynaide compounds in mortar of facilities exposed to HCN. 

The fact is that the walls of the delousing buildings are saturated through and through with hydrogen cyanide compounds, of which only a part becomes visible as iron blue, predominantly in damp areas and at the surfaces due to accumulation processes. These facts can be explained only as a result of fumigations with HCN. 

The cyanide ion is a highly reactive ion, which joins with metals to form very stable complex salts. The best-known complex salts are the yellow and red iron cyanides. These compounds form when iron ions combine with cyanide with the iron(II) ion, the yellow ferrocyanide forms, and with the iron(III) ion, the red ferricyanide is produced ... 

In the presence of excess iron(II) or iron(III) ions, the yellow or red iron cyanide then reacts to form blue compounds which are described in the literature as Berlin Blue and Turnbull s Blue, respectively ... 

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