Cobalt oxide-aqueous solution

In Situ Mdssbauer Studies of Metal Oxide-Aqueous Solution Interfaces with Adsorbed Cobalt-57 and Antimony-119 Ions... 

Ambe, F., Ambe, S., Okada, T., and Sekizawa, H. (1986). In situ Mossbauer studies of metal oxide-aqueous solution interfaces with adsorbed cobalt-57 and antimony-119 ions. In Geochemical Processes at Mineral Surfaces, ed. Davis, J. A., and Hayes, K. 

Similarity with cobalt is also apparent in the affinity of Rh and iH for ammonia and amines. The kinetic inertness of the ammines of Rh has led to the use of several of them in studies of the trans effect (p. 1163) in octahedral complexes, while the ammines of Ir are so stable as to withstand boiling in aqueous alkali. Stable complexes such as [M(C204)3], [M(acac)3] and [M(CN)5] are formed by all three metals. Force constants obtained from the infrared spectra of the hexacyano complexes indicate that the M--C bond strength increases in the order Co < Rh < [r. Like cobalt, rhodium too forms bridged superoxides such as the blue, paramagnetic, fCl(py)4Rh-02-Rh(py)4Cll produced by aerial oxidation of aqueous ethanolic solutions of RhCL and pyridine.In fact it seems likely that many of the species produced by oxidation of aqueous solutions of Rh and presumed to contain the metal in higher oxidation states, are actually superoxides of Rh . ... 

Carbonyl Nitric Oxides. Another group of metal-carbonyl complexes, worthy of investigation as CVD precursors, consists of the carbonyl nitric oxides. In these complexes, one (or more) CO group is replaced by NO. An example is cobalt nitrosyl tricarbonyl, CoNO(CO)3, which is a preferred precursor for the CVD of cobalt. It is a liquid with a boiling point of 78.6°C which decomposes at 66°C. It is prepared by passing NO through an aqueous solution of cobalt nitrate and potassium cyanide and potassium hydroxide. ... 

It is very common for inorganic chemists to neglect or ignore the presence of solvent molecules coordinated to a metal centre. In some cases, this is just carelessness, or laziness, as in the description of an aqueous solution of cobalt(ii) nitrate as containing Co ions. Except in very concentrated solutions, the actual solution species is [Co(H20)6] . In other cases, it is not always certain exactly what ligands remain coordinated to the metal ion in solution, or how many solvent molecules become coordinated. Solutions of iron(iii) chloride in water contain a mixture of complex ions containing a variety of chloride, water, hydroxide and oxide ligands. 

The hexamine cobalt (II) complex is used as a coordinative catalyst, which can coordinate NO to form a nitrosyl ammine cobalt complex, and O2 to form a u -peroxo binuclear bridge complex with an oxidability equal to hydrogen peroxide, thus catalyze oxidation of NO by O2 in ammoniac aqueous solution. Experimental results under typical coal combusted flue gas treatment conditions on a laboratory packed absorber- regenerator setup show a NO removal of more than 85% can be maitained constant. 

In the present study the surface chemistry of birnessite and of birnessite following the interaction with aqueous solutions of cobalt(II) and cobalt(III) amine complexes as a function of pH has been investigated using two surface sensitive spectroscopic techniques. X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The significant contribution that such an investigation can provide rests in the information obtained regarding the chemical nature of the neat metal oxide and of the metal oxide/metal ion adsorbate surfaces, within about the top 50 of the material surface. The chemical... 

Let us start with the Ni(II) complexes of the already mentioned scorpiand diammac (6,13-diammino-6,13-dimethyl-1,4,8,11-tetraazacy-clotetradecane) in its two cis and trans conformations. In contrast to the previously mentioned chromium-, iron-, and cobalt-diammac complexes, in which the geometry of [M(fra s-diammac)]" + was substantially octahedral and that of the [M(cw-diammac)]" + was substantially trigonal prismatic, in the case of both [Nif/raws-diammac)]2+ and [Ni(m-diammac)]2 + the structural differences are attenuated and both can be viewed as more or less distorted octahedral geometries, with two sets of averaged Ni-N bond lengths of 2.07 A and 2.13 A, respectively.161 162 This is reflected by the fact that both the two complexes exhibit in aqueous solution a chemically reversible Ni(II)/Ni(III) oxidation ([Nif/raws-diammac)]2 + E° = + 0.67 V vs. SHE [Ni(m-diammac)]2 + ... 

It would be hardly possible to do full justice to the kinetic behavior of cobalt even in a book devoted to that subject. Only some important features will be emphasized. The stable oxidation states in aqueous solution are Co(II) and Co(III). 

Besides Scheme 3.45, one more case of ferrocenylammoninm oxidation deserves to be considered. That is, the chemical oxidation of the confined species. fV-(ferrocenylmethylene)-A/,A/,Af-trimethylam-monium forms a remarkably stable inclnsion complex with cucurbituril (Jeon et al. 2005). Yuan and Macartney (2007) used aqueous solution of the bis(2,6-pyridinedicarboxylato)cobaltate(III) ion for comparative oxidation of free and included compounds. This oxidant does not bind to curcubituril. As it turned out, the inclusion significantly reduces the rate constants for the ferrocenyl-ferroceniumly transition. One of the important causes of the retardation observed is the steric hindrance due to close approach of the oxidant to the encapsulated ferrocene (Yuan and Macartney 2007). 

The hexahydrate forms emerald green monochnic crystals hygroscopic density 2.05 g/cm isomorphous with corresponding cobalt salt melts at 56.7°C loses water on heating, decomposing to nickel oxide very soluble in water aqueous solution acidic soluble in ethanol. 

In aqueous solution Cobalt(III) ion is able to oxidize under... 

Cobalt(III) is a potent oxidant in an aqueous solution and, in the absence of a complexing agent that can stabilize cobalt(III), it is rapidly reduced to cobalt(II) with the concomitant oxidation of water to dioxygen ... 

In a classic study, Hume and KolthofF[13] obtained polarographic evidence that, in a 1 M aqueous solution of potassium cyanide, Co(H20)(CN)s is irreversibly reduced at a dropping mercury electrode to a cobalt(I) species, the composition of which was not elucidated. furthermore, the cobalt(I) complex was reported to undergo neither oxidation nor reduction. In addition, the cobalt(III) complex, Co(H20)(CN)5 , was seen to be reducible at the dropping mercury electrode, whereas Co(CN)6 is not electroactive. In earlier work [14], cobalt(II) cyanide complexes were reduced electrolytically to cobalt(I) cyanide species. 

The liquid-phase oxidation of acrolein (AL), the reaction products, their routes of formation, reaction in the absence or presence of catalysts such as acetylacetonates (acac) and naphthenates (nap) of transition metals and the influence of reaction factors were discussed in an earlier paper (22). The coordinating state of cobalt acetylacetonate in the earlier stage of the reaction depends on the method of addition to the reaction system (25, 26). The catalyst, Co(acac)2-H20-acrolein, which was synthesized by mixing a solution of Co(acac)2 in benzene with a saturated aqueous solution, decreases the induction period of oxygen uptake and increases the rate of oxygen absorption. The acrolein of the catalyst coordinated with its cobalt through the lone pair of electrons of the aldehyde oxygen. Therefore, it is believed that the coordination of acrolein with a catalyst is necessary to initiate the oxidation reaction (10). 

In this reaction, oxalate ion may be oxidized intramolecularly by cobalt(III) ion, but it is interesting to compare the three different systems in w hich there are three, two, or one oxalate ions with the cobalt(III) cation. The last one can be boiled in l.OM add for an hour and nothing happens. In the first one, decomposition will occur very readily in aqueous solution at 50°C., so that oxalate exchange can t be measured, for instance. The middle one has not been studied in any detail yet, as far as I know, but there is oxidation-reduction in this too, though much slower than in the first. I wonder if this inhibiting effect of the nonreacting ligand, the diamine, on the oxidation has any simple explanation. 

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