Complexation with iron/cobalt

Sulphuric acid is not recommended, because sulphate ions have a certain tendency to form complexes with iron(III) ions. Silver, copper, nickel, cobalt, titanium, uranium, molybdenum, mercury (>lgL-1), zinc, cadmium, and bismuth interfere. Mercury(I) and tin(II) salts, if present, should be converted into the mercury(II) and tin(IV) salts, otherwise the colour is destroyed. Phosphates, arsenates, fluorides, oxalates, and tartrates interfere, since they form fairly stable complexes with iron(III) ions the influence of phosphates and arsenates is reduced by the presence of a comparatively high concentration of acid. 

Mapsi et al. [16] reported the use of a potentiometric method for the determination of the stability constants of miconazole complexes with iron(II), iron(III), cobalt(II), nickel(II), copper(II), and zinc(II) ions. The interaction of miconazole with the ions was determined potentiometrically in methanol-water (90 10) at an ionic force of 0.16 and at 20 °C. The coordination number of iron, cobalt, and nickel was 6 copper and zinc show a coordination number of 4. The values of the respected log jSn of these complexes were calculated by an improved Scatchard (1949) method and they are in agreement with the Irving-Williams (1953) series of Fe2+ < Co2+ < Ni2 < Cu2+ < Zn2+. 

The perchlorate salts of the complexes with divalent cobalt, nickel, and particularly iron (analogous to IV, p. S-15) are potentially explosive, and storage for more than 4 weeks is not advised. 

The action of nitric oxide on iron, cobalt, and nickel salts has been previously discussed. Complexes with iron salts and nitrosyl have been discussed by W. Manchot13 and co-workers, A. Werner, K. A. Hofmann and O. F. Wrede,... 

There is a certain analogy between the aromatic anions of cyclopentadienide (C5H5 ) and boratabenzene (C5H6B ). l-Methylbora-2,5-cyclohexadienehas a more acidic proton connected to the, sp3-hybridized ring carbon atom than cyclopentadi-ene, due to the same tendency of aromatic anion formation [252, 253]. The related 1-phenyl-1,4-dihydroborabenzene affords the lithium salt of 1-phenylborataben-zene on treatment with tert-butyllithium. Like metallic complexes such as ferrocene formed by cyclopentadiene, boratabenzene also forms such sandwich -complexes with iron and cobalt. The iron complex can be acetylated under Friedel-Crafts conditions. 

Recent infrared absorption and x-ray diffraction studies have shown that metals of the first transition series normally form M—N bonds with the thiocyanate group.12-14 X-ray diffraction studies have shown that the isothiocyanato groups are trans to each other in the tetrapyridine complexes of iron, cobalt, and nickel 14-17 this configuration has been confirmed for the iron compound by electronic spectra.4... 

Tn transition Group Villa, complexes of iron, cobalt, nickel and rhodium are active in CO3 dcoxygenation. The reactivity of a series of metal carbonyl anions with carbon dioxide has been found to parallel their relative nucleophilicities. The highly nucleophilic (CpFefCO) ] reacts to form the dimer [CpFefCO) ] 2 and carbonate, whereas (CofCO) ]" is unrcactivc [284]. 

The disubstituted polypyridine derivatives, 4, 4" -bis(methylthio)-2,2 6, 2" 6", 2" 6", 2""-quinquepyridine (45) and 4, 4""-bis(methylthio)- 2,2 6, 2" 6",2" 6", 2"" 6 ", 2 ""-sexipyridine (46), in which the alkylthio groups are present on the 4-positions of the penultimate pyridines (with respect to each end) also form bimetallic double-stranded helical complexes with iron(II), cobalt(II), nickel(II), zinc(II) and palladium(II). With the first of these ligands, the palladium species is of type... 

Transitory outbreaks of gushing have been observed due to the precipitation of microcrystals of calcium oxalate while other outbreaks have been associated with the presence of heavy metals, in particular, iron, nickel, tin, and molybdenum. Such outbreaks can often be cured by the addition of EDTA to the beer which forms complexes with calcium and heavy metals. The balance of heavy metals in beer is obviously critical for it was observed that iron and nickel only caused gushing when complexed with isohumulone. Cobalt, on the other hand, shows little tendency to cause gushing and, indeed it was found during one severe epidemic of gushing that the addition of 0-2-1 0 ppm of cobalt dramatically reduced the incidence of the complaint. However, in another case it was without effect. 

Arana, C., S. Yan, M. Keshavaraz, K.K.T. Pots, and H.D. Ahruna (1992). Electro-catalytic reduction of carbon dioxide with iron, cobalt, and nickel complexes of terdentate ligands. Inorg Chem. 31, 3680-3682. 

In 2010 [95], Ozaki and collaborators mixed a furan resin with iron, cobalt, or nickel acetylacetonates and carbonized the mixture in N2 at 600 to 1,000 °C. The resulting material was ball milled and then acid washed to remove excess metal. The best catalyst was obtained with the Co complex carbonized at 800 °C. Its Fonset in 0.5 M H2SO4 was 0.62 V vs. RHE. The catalyst had a specific surface area of 211 m /g and its N/C ratio was 0.035. Its ORR activity was explained by the formation of carbon nanoshells, but also by N doping of the catalyst carbonaceous material. 

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